only the length of a tunnel by that method of measuring, and determine
the depth of a shaft by another method; that is, by the method by which
cords are re-stretched on a level part of the mountain or in a valley,
or in flat fields, and are measured again. Some, however, do not employ
this method in surveying the depth of a shaft and the length of a
tunnel, but use only two cords, a graduated hemicycle[18] and a rod half
a fathom long. They suspend in the shaft one cord, fastened from the
upper pole and weighted, just as the others do. Fastened to the upper
end of this cord, they stretch another right down the slope of the
mountain to the bottom of the mouth of the tunnel and fix it to the
ground. Then to the upper part of this second cord they apply on its
lower side the broad part of a hemicycle. This consists of half a
circle, the outer margin of which is covered with wax, and within this
are six semi-circular lines. From the waxed margin through the first
semi-circular line, and reaching to the second, there proceed straight
lines converging toward the centre of the hemicycle; these mark the
middles of intervening spaces lying between other straight lines which
extend to the fourth semi-circular line. But all lines whatsoever, from
the waxed margin up to the fourth line, whether they go beyond it or
not, correspond with the graduated lines which mark the minor spaces of
a rod. Those which go beyond the fourth line correspond with the lines
marking the major spaces on the rod, and those which proceed further,
mark the middle of the intervening space which lies between the others.
The straight lines, which run from the fifth to the sixth semi-circular
line, show nothing further. Nor does the line which measures the half,
show anything when it has already passed from the sixth straight line to
the base of the hemicycle. When the hemicycle is applied to the cord, if
its tongue indicates the sixth straight line which lies between the
second and third semi-circular lines, the surveyor counts on the rod six
lines which separate the minor spaces, and if the length of this portion
of the rod be taken from the second cord, as many times as the cord
itself is half-fathoms long, the remaining length of cord shows the
distance the tunnel must be driven to reach under the shaft. But if he
sees that the tongue has gone so far that it marks the sixth line
between the fourth and fifth semi-circular lines, he counts six lines
which separate the major spaces on the rod; and this entire space is
deducted from the length of the second cord, as many times as the number
of whole fathoms which the cord contains; and then, in like manner, the
remaining length of cord shows us the distance the tunnel must be driven
to reach under the shaft.[19]
[Illustration 139 (Surveying Triangle): Stretched cords: A--First cord.
B--Second cord. C--Third cord. D--Triangle.]
Both these surveyors, as well as the others, in the first place make
use of the haulage rope. These they measure by means of others made of
linden bark, because the latter do not stretch at all, while the former
become very slack. These cords they stretch on the surveyor's field, the
first one to represent the parts of mountain slopes which descend
obliquely. Then the second cord, which represents the length of the
tunnel to be driven to reach the shaft, they place straight, in such a
direction that one end of it can touch the lower end of the first cord;
then they similarly lay the third cord straight, and in such a direction
that its upper end may touch the upper end of the first cord, and its
lower end the other extremity of the second cord, and thus a triangle is
formed. This third cord is measured by the instrument with the index, to
determine its relation to the perpendicular; and the length of this cord
shows the depth of the shaft.
[Illustration 140 (Surveying Triangles): Stretched cords: A--First.
B--Second. B--Third. C--Fourth. C--Fifth. D--Quadrangle.]
Some surveyors, to make their system of measuring the depth of a shaft
more certain, use five stretched cords: the first one descending
obliquely; two, that is to say the second and third, for ascertaining
the length of the tunnel; two for the depth of the shaft; in which way
they form a quadrangle divided into two equal triangles, and this tends
to greater accuracy.
These systems of measuring the depth of a shaft and the length of a
tunnel, are accurate when the vein and also the shaft or shafts go down
to the tunnel vertically or inclined, in an uninterrupted course. The
same is true when a tunnel runs straight on to a shaft. But when each of
them bends now in this, now in that direction, if they have not been
completely driven and sunk, no living man is clever enough to judge how
far they are deflected from a straight course. But if the whole of
either one of the two has been excavated its full distance, then we can
estimate more easily the length of one, or the depth of the other; and
so the location of the tunnel, which is below a newly-started shaft, is
determined by a method of surveying which I will describe. First of all
a tripod is fixed at the mouth of the tunnel, and likewise at the mouth
of the shaft which has been started, or at the place where the shaft
will be started. The tripod is made of three stakes fixed to the ground,
a small rectangular board being placed upon the stakes and fixed to
them, and on this is set a compass. Then from the lower tripod a
weighted cord is let down perpendicularly to the earth, close to which
cord a stake is fixed in the ground. To this stake another cord is tied
and drawn straight into the tunnel to a point as far as it can go
without being bent by the hangingwall or the footwall of the vein. Next,
from the cord which hangs from the lower tripod, a third cord likewise
fixed is brought straight up the sloping side of the mountain to the
stake of the upper tripod, and fastened to it. In order that the
measuring of the depth of the shaft may be more certain, the third cord
should touch one and the same side of the cord hanging from the lower
tripod which is touched by the second cord--the one which is drawn into
the tunnel. All this having been correctly carried out, the surveyor,
when at length the cord which has been drawn straight into the tunnel is
about to be bent by the hangingwall or footwall, places a plank in the
bottom of the tunnel and on it sets the orbis, an instrument which has
an indicator peculiar to itself. This instrument, although it also has
waxed circles, differs from the other, which I have described in the
third book. But by both these instruments, as well as by a rule and a
square, he determines whether the stretched cords reach straight to the
extreme end of the tunnel, or whether they sometimes reach straight, and
are sometimes bent by the footwall or hangingwall. Each instrument is
divided into parts, but the compass into twenty-four parts, the orbis
into sixteen parts; for first of all it is divided into four principal
parts, and then each of these is again divided into four. Both have
waxed circles, but the compass has seven circles, and the orbis only
five circles. These waxed circles the surveyor marks, whichever
instrument he uses, and by the succession of these same marks he notes
any change in the direction in which the cord extends. The orbis has an
opening running from its outer edge as far as the centre, into which
opening he puts an iron screw, to which he binds the second cord, and by
screwing it into the plank, fixes it so that the orbis may be immovable.
He takes care to prevent the second cord, and afterward the others which
are put up, from being pulled off the screw, by employing a heavy iron,
into an opening of which he fixes the head of the screw. In the case of
the compass, since it has no opening, he merely places it by the side of
the screw. That the instrument does not incline forward or backward, and
in that way the measurement become a greater length than it should be,
he sets upon the instrument a standing plummet level, the tongue of
which, if the instrument is level, indicates no numbers, but the point
from which the numbers start.
[Illustration 142 (Compass): Compass. A, B, C, D, E, F, G are the seven
waxed circles.]
[Illustration 142A (Orbis): A, B, C, D, E--Five waxed circles of the
_orbis_. F--Opening of same. G--Screw. H--Perforated iron.]
[Illustration 143 (Miner using level): A--Standing plummet level.
B--Tongue. C--Level and tongue.]
When the surveyor has carefully observed each separate angle of the
tunnel and has measured such parts as he ought to measure, then he lays
them out in the same way on the surveyor's field[20] in the open air,
and again no less carefully observes each separate angle and measures
them. First of all, to each angle, according as the calculation of his
triangle and his art require it, he lays out a straight cord as a line.
Then he stretches a cord at such an angle as represents the slope of
the mountain, so that its lower end may reach the end of the straight
cord; then he stretches a third cord similarly straight and at such an
angle, that with its upper end it may reach the upper end of the second
cord, and with its lower end the last end of the first cord. The length
of the third cord shows the depth of the shaft, as I said before, and at
the same time that point on the tunnel to which the shaft will reach
when it has been sunk.
If one or more shafts reach the tunnel through intermediate drifts and
shafts, the surveyor, starting from the nearest which is open to the
air, measures in a shorter time the depth of the shaft which requires to
be sunk, than if he starts from the mouth of the tunnel. First of all he
measures that space on the surface which lies between the shaft which
has been sunk and the one which requires to be sunk. Then he measures
the incline of all the shafts which it is necessary to measure, and the
length of all the drifts with which they are in any way connected to the
tunnel. Lastly, he measures part of the tunnel; and when all this is
properly done, he demonstrates the depth of the shaft and the point in
the tunnel to which the shaft will reach. But sometimes a very deep
straight shaft requires to be sunk at the same place where there is a
previous inclined shaft, and to the same depth, in order that loads may
be raised and drawn straight up by machines. Those machines on the
surface are turned by horses; those inside the earth, by the same means,
and also by water-power. And so, if it becomes necessary to sink such a
shaft, the surveyor first of all fixes an iron screw in the upper part
of the old shaft, and from the screw he lets down a cord as far as the
first angle, where again he fixes a screw, and again lets down the cord
as far as the second angle; this he repeats again and again until the
cord reaches to the bottom of the shaft. Then to each angle of the cord
he applies a hemicycle, and marks the waxed semi-circle according to the
lines which the tongue indicates, and designates it by a number, in case
it should be moved; then he measures the separate parts of the cord with
another cord made of linden bark. Afterward, when he has come back out
of the shaft, he goes away and transfers the markings from the waxed
semi-circle of the hemicycle to an orbis similarly waxed. Lastly, the
cords are stretched on the surveyor's field, and he measures the angles,
as the system of measuring by triangles requires, and ascertains which
part of the footwall and which part of the hangingwall rock must be cut
away in order that the shaft may descend straight. But if the surveyor
is required to show the owners of the mine, the spot in a drift or a
tunnel in which a shaft needs to be raised from the bottom upward, that
it should cut through more quickly, he begins measuring from the bottom
of the drift or tunnel, at a point beyond the spot at which the bottom
of the shaft will arrive, when it has been sunk. When he has measured
the part of the drift or tunnel up to the first shaft which connects
with an upper drift, he measures the incline of this shaft by applying a
hemicycle or orbis to the cord. Then in a like manner he measures the
upper drift and the incline shaft which is sunk therein toward which a
raise is being dug, then again all the cords are stretched in the
surveyor's field, the last cord in such a way that it reaches the first,
and then he measures them. From this measurement is known in what part
of the drift or tunnel the raise should be made, and how many fathoms
of vein remain to be broken through in order that the shaft may be
connected.
I have described the first reason for surveying; I will now describe
another. When one vein comes near another, and their owners are
different persons who have late come into possession, whether they drive
a tunnel or a drift, or sink a shaft, they may encroach, or seem to
encroach, without any lawful right, upon the boundaries of the older
owners, for which reason the latter very often seek redress, or take
legal proceedings. The surveyor either himself settles the dispute
between the owners, or by his art gives evidence to the judges for
making their decision, that one shall not encroach on the mine of the
other. Thus, first of all he measures the mines of each party with a
basket rope and cords of linden bark; and having applied to the cords an
orbis or a compass, he notes the directions in which they extend. Then
he stretches the cords on the surveyor's field; and starting from that
point whose owners are in possession of the old meer toward the other,
whether it is in the hanging or footwall of the vein, he stretches a
cross-cord in a straight line, according to the sixth division of the
compass, that is, at a right angle to the vein, for a distance of three
and a half fathoms, and assigns to the older owners that which belongs
to them. But if both ends of one vein are being dug out in two tunnels,
or drifts from opposite directions, the surveyor first of all considers
the lower tunnel or drift and afterward the upper one, and judges how
much each of them has risen little by little. On each side strong men
take in their hands a stretched cord and hold it so that there is no
point where it is not strained tight; on each side the surveyor supports
the cord with a rod half a fathom long, and stays the rod at the end
with a short stick as often as he thinks it necessary. But some fasten
cords to the rods to make them steadier. The surveyor attaches a
suspended plummet level to the middle of the cord to enable him to
calculate more accurately on both sides, and from this he ascertains
whether one tunnel has risen more than another, or in like manner one
drift more than another. Afterward he measures the incline of the shafts
on both sides, so that he can estimate their position on each side. Then
he easily sees how many fathoms remain in the space which must be broken
through. But the grade of each tunnel, as I said, should rise one fathom
in the distance of one hundred fathoms.
[Illustration 146 (Plummet cord and weight): Indicator of a suspended
plummet level.]
[Illustration 147 (Compass): A--Needle of the instrument. B--Its tongue.
C, D, E--Holes in the tongue.]
The Swiss surveyors, when they wish to measure tunnels driven into the
highest mountains, also use a rod half a fathom long, but composed of
three parts, which screw together, so that they may be shortened. They
use a cord made of linden bark to which are fastened slips of paper
showing the number of fathoms. They also employ an instrument peculiar
to them, which has a needle; but in place of the waxed circles they
carry in their hands a chart on which they inscribe the readings of the
instrument. The instrument is placed on the back part of the rod so that
the tongue, and the extended cord which runs through the three holes in
the tongue, demonstrates the direction, and they note the number of
fathoms. The tongue shows whether the cord inclines forward or backward.
The tongue does not hang, as in the case of the suspended plummet
level, but is fixed to the instrument in a half-lying position. They
measure the tunnels for the purpose of knowing how many fathoms they
have been increased in elevation; how many fathoms the lower is distant
from the upper one; how many fathoms of interval is not yet pierced
between the miners who on opposite sides are digging on the same vein,
or cross-stringers, or two veins which are approaching one another.
But I return to our mines. If the surveyor desires to fix the boundaries
of the meer within the tunnels or drifts, and mark to them with a sign
cut in the rock, in the same way that the _Bergmeister_ has marked these
boundaries above ground, he first of all ascertains, by measuring in the
manner which I have explained above, which part of the tunnel or drift
lies beneath the surface boundary mark, stretching the cords along the
drifts to a point beyond that spot in the rock where he judges the mark
should be cut. Then, after the same cords have been laid out on the
surveyor's field, he starts from that upper cord at a point which shows
the boundary mark, and stretches another cross-cord straight downward
according to the sixth division of the compass--that is at a right
angle. Then that part of the lowest cord which lies beyond the part to
which the cross-cord runs being removed, it shows at what point the
boundary mark should be cut into the rock of the tunnel or drift. The
cutting is made in the presence of the two Jurors and the manager and
the foreman of each mine. For as the _Bergmeister_ in the presence of
these same persons sets the boundary stones on the surface, so the
surveyor cuts in the rock a sign which for this reason is called the
boundary rock. If he fixes the boundary mark of a meer in which a shaft
has recently begun to be sunk on a vein, first of all he measures and
notes the incline of that shaft by the compass or by another way with
the applied cords; then he measures all the drifts up to that one in
whose rock the boundary mark has to be cut. Of these drifts he measures
each angle; then the cords, being laid out on the surveyor's field, in a
similar way he stretches a cross-cord, as I said, and cuts the sign on
the rock. But if the underground boundary rock has to be cut in a drift
which lies beneath the first drift, the surveyor starts from the mark in
the first drift, notes the different angles, one by one, takes his
measurements, and in the lower drift stretches a cord beyond that place
where he judges the mark ought to be cut; and then, as I said before,
lays out the cords on the surveyor's field. Even if a vein runs
differently in the lower drift from the upper one, in which the first
boundary mark has been cut in the rock, still, in the lower drift the
mark must be cut in the rock vertically beneath. For if he cuts the
lower mark obliquely from the upper one some part of the possession of
one mine is taken away to its detriment, and given to the other.
Moreover, if it happens that the underground boundary mark requires to
be cut in an angle, the surveyor, starting from that angle, measures one
fathom toward the front of the mine and another fathom toward the back,
and from these measurements forms a triangle, and dividing its middle by
a cross-cord, makes his cutting for the boundary mark.
Lastly, the surveyor sometimes, in order to make more certain, finds the
boundary of the meers in those places where many old boundary marks are
cut in the rock. Then, starting from a stake fixed on the surface, he
first of all measures to the nearest mine; then he measures one shaft
after another; then he fixes a stake on the surveyors' field, and making
a beginning from it stretches the same cords in the same way and
measures them, and again fixes in the ground a stake which for him will
signify the end of his measuring. Afterward he again measures
underground from that spot at which he left off, as many shafts and
drifts as he can remember. Then he returns to the surveyor's field, and
starting again from the second stake, makes his measurements; and he
does this as far as the drift in which the boundary mark must be cut in
the rock. Finally, commencing from the stake first fixed in the ground,
he stretches a cross-cord in a straight line to the last stake, and this
shows the length of the lowest drift. The point where they touch, he
judges to be the place where the underground boundary mark should be
cut.
END OF BOOK V.
FOOTNOTES:
[1] It has been suggested that we should adopt throughout this volume
the mechanical and mining terms used in English mines at Agricola's
time. We believe, however, that but a little inquiry would illustrate
the undesirability of this course as a whole. Where there is choice in
modern miner's nomenclature between an old and a modern term, we have
leaned toward age, if it be a term generally understood. But except
where the subject described has itself become obsolete, we have revived
no obsolete terms. In substantiation of this view, we append a few
examples of terms which served the English miner well for centuries,
some of which are still extant in some local communities, yet we believe
they would carry as little meaning to the average reader as would the
reproduction of the Latin terms coined by Agricola.
Rake = A perpendicular vein.
Woughs = Walls of the vein.
Shakes = Cracks in the walls.
Flookan = Gouge.
Bryle = Outcrop.
Hade = Incline or underlay of the vein.
Dawling = Impoverishment of the vein.
Rither = A "horse" in a vein.
Twitches = "Pinching" of a vein.
Slough = Drainage tunnel.
Sole = Lowest drift.
Stool = Face of a drift or stope.
Winds }
Turn } = Winze.
Dippas}
Grove = Shaft.
Dutins = Set of timber.
Stemple = Post or stull.
Laths = Lagging.
As examples of the author's coinage and adaptations of terms in this
book we may cite:--
_Fossa latens_ = Drift.
_Fossa latens transversa_ = Crosscut.
_Tectum_ = Hangingwall.
_Fundamentum_ = Footwall.
_Tigna per intervalla posita_ = Wall plate.
_Arbores dissectae_ = Lagging.
_Formae_ = Hitches.
We have adopted the term "tunnel" for openings by way of outlet to the
mine. The word in this narrow sense is as old as "adit," a term less
expressive and not so generally used in the English-speaking mining
world. We have for the same reason adopted the word "drift" instead of
the term "level" so generally used in America, because that term always
leads to confusion in discussion of mine surveys. We may mention,
however, that the term "level" is a heritage from the Derbyshire mines,
and is of an equally respectable age as "drift."
[2] See note on p. 46-47. The _canales_, as here used, were the openings
in the earth, in which minerals were deposited.
[3] This statement, as will appear by the description later on, refers
to the depth of winzes or to the distance between drifts, that is "the
lift." We have not, however, been justified in using the term "winze,"
because some of these were openings to the surface. As showing the
considerable depth of shafts in Agricola's time, we may quote the
following from _Bermannus_ (p. 442): "The depths of our shafts forced us
to invent hauling machines suitable for them. There are some of them
larger and more ingenious than this one, for use in deep shafts, as, for
instance, those in my native town of Geyer, but more especially at
Schneeberg, where the shaft of the mine from which so much treasure was
taken in our memory has reached the depth of about 200 fathoms (feet?),
wherefore the necessity of this kind of machinery. _Naevius_: What an
enormous depth! Have you reached the Inferno? _Bermannus_: Oh, at
Kuttenberg there are shafts more than 500 fathoms (feet?) deep.
_Naevius_: And not yet reached the Kingdom of Pluto?" It is impossible
to accept these as fathoms, as this would in the last case represent
3,000 feet vertically. The expression used, however, for fathoms is
_passus_, presumably the Roman measure equal to 58.1 inches.
[4] _Cavernos_. The Glossary gives _drusen_, our word _drusy_ having had
this origin.
[5] _Purum_,--"pure." _Interpretatio_ gives the German as
_gedigen_,--"native."
[6] _Rudis_,--"Crude." By this expression the author really means ores
very rich in any designated metal. In many cases it serves to indicate
the minerals of a given metal, as distinguished from the metal itself.
Our system of mineralogy obviously does not afford an acceptable
equivalent. Agricola (_De Nat. Foss._, p. 360) says: "I find it
necessary to call each genus (of the metallic minerals) by the name of
its own metal, and to this I add a word which differentiates it from the
pure (_puro_) metal, whether the latter has been mined or smelted; so I
speak of _rudis_ gold, silver, quicksilver, copper, tin, bismuth, lead,
or iron. This is not because I am unaware that Varro called silver
_rudis_ which had not yet been refined and stamped, but because a word
which will distinguish the one from the other is not to be found."
[7] The reasons for retaining the Latin weights are given in the
Appendix on Weights and Measures. A _centumpondium_ weighs 70.6 lbs.
avoirdupois, an _uncia_ 412.2 Troy grains, therefore, this value is
equal to 72 ounces 18 pennyweights per short ton.
[8] Agricola mentions many minerals in _De Re Metallica_, but without
such description as would make possible a hazard at their identity. From
his _De Natura Fossilium_, however, and from other mineralogies of the
16th Century, some can be fully identified and others surmised. While we
consider it desirable to set out the probable composition of these
minerals, on account of the space required, the reasons upon which our
opinion has been based cannot be given in detail, as that would require
extensive quotations. In a general way, we have throughout the text
studiously evaded the use of modern mineralogical terms--unless the term
used to-day is of Agricola's age--and have adopted either old English
terms of pre-chemistry times or more loose terms used by common miners.
Obviously modern mineralogic terms imply a precision of knowledge not
existing at that period. It must not be assumed that the following is by
any means a complete list of the minerals described by Agricola, but
they include most of those referred to in this chapter. His system of
mineralogy we have set out in note 4, p. 1, and it requires no further
comment here. The grouping given below is simply for convenience and
does not follow Agricola's method. Where possible, we tabulate in
columns the Latin term used in _De Re Metallica_; the German equivalent
given by the Author in either the _Interpretatio_ or the Glossary; our
view of the probable modern equivalent based on investigation of his
other works and other ancient mineralogies, and lastly the terms we have
adopted in the text. The German spelling is that given in the original.
As an indication of Agricola's position as a mineralogist, we mark with
an asterisk the minerals which were first specifically described by him.
We also give some notes on matters of importance bearing on the
nomenclature used in _De Re Metallica_. Historical notes on the chief
metals will be found elsewhere, generally with the discussion of
smelting methods. We should not omit to express our indebtedness to
Dana's great "System of Mineralogy," in the matter of correlation of
many old and modern minerals.
GOLD MINERALS. Agricola apparently believed that there were various gold
minerals, green, yellow, purple, black, etc. There is nothing, however,
in his works that permits of any attempt to identify them, and his
classification seems to rest on gangue colours.
SILVER MINERALS.
_Argentum purum in _Gedigen silber_ -- *Native silver
venis reperitur_
_Argentum rude_ _Gedigen silber -- _Rudis_ silver, or
ertz_ pure silver
minerals
_Argentum rude _Glas ertz_ Argentite *Silver glance
plumbei coloris_ (Ag_{2}S)
_Argentum rude _Rot gold ertz_ Pyrargyrite *Red silver
rubrum_ (Ag_{3}SbS_{3})
_Argentum rude _Durchsichtig Proustite *Ruby silver
rubrum rod gulden (Ag_{3}AsS_{3})
translucidum_ ertz_
_Argentum rude _Weis rod gulden -- White silver
album_ ertz: Dan es
ist frisch wie
offtmals rod
gulden ertz
pfleget zusein_
_Argentum rude _Gedigen Part Bromyrite Liver-coloured
jecoris leberfarbig (Ag Br) silver
colore_ ertz_
_Argentum rude _Gedigen -- Yellow silver
luteum_ geelertz_
_Argentum rude _Gedigen graw } { *Grey silver
cineraceum_ ertz_ } Part Cerargurite {
} (Ag Cl) (Horn {
_Argentum rude _Gedigen } Silver) Part { *Black silver
nigrum_ schwartz ertz_ } Stephanite {
} (Ag_{5}SbS_{4}) {
_Argentum rude _Gedigen braun } { *Purple silver
purpureum_ ertz_ } {
The last six may be in part also alteration products from all silver
minerals.
The reasons for indefiniteness in determination usually lie in the
failure of ancient authors to give sufficient or characteristic
descriptions. In many cases Agricola is sufficiently definite as to
assure certainty, as the following description of what we consider to be
silver glance, from _De Natura Fossilium_ (p. 360), will indicate:
"Lead-coloured _rudis_ silver is called by the Germans from the word
glass (_glasertz_), not from lead. Indeed, it has the colour of the
latter or of galena (_plumbago_), but not of glass, nor is it
transparent like glass, which one might indeed expect had the name been
correctly derived. This mineral is occasionally so like galena in
colour, although it is darker, that one who is not experienced in
minerals is unable to distinguish between the two at sight, but in
substance they differ greatly from one another. Nature has made this
kind of silver out of a little earth and much silver. Whereas galena
consists of stone and lead containing some silver. But the distinction
between them can be easily determined, for galena may be ground to
powder in a mortar with a pestle, but this treatment flattens out this
kind of _rudis_ silver. Also galena, when struck by a mallet or bitten
or hacked with a knife, splits and breaks to pieces; whereas this silver
is malleable under the hammer, may be dented by the teeth, and cut with
a knife."
COPPER MINERALS.
_Aes purum _Gedigen kupfer_ Native copper Native copper
fossile_
_Aes rude _Kupferglas ertz_ Chalcocite *Copper glance
plumbei (Cu_{2}S)
coloris_
_Chalcitis_ _Rodt atrament_ A decomposed _Chalcitis_ (see
copper or notes on p. 573)
iron sulphide
_Pyrites aurei } _Geelkis oder { Part chalcopyrite Copper pyrites
colore_ } kupferkis_ { (Cu Fe S) part
} { bornite
_Pyrites aerosus_ } { (Cu_{3}FeS_{3})
_Caeruleum_ _Berglasur_ Azurite Azure
_Chrysocolla_ _Berggruen und { Part chrysocolla Chrysocolla (see
schifergruen_ { Part Malachite note 7, p. 560)
_Molochites_ _Molochit_ Malachite Malachite
_Lapis aerarius_ _Kupfer ertz_ -- Copper ore
_Aes caldarium } _Lebeter kupfer_ { When used for
rubrum fuscum_ } { an ore, is *Ruby copper ore
or } { probably
_Aes sui coloris_ } _Rotkupfer_ { cuprite
_Aes nigrum_ _Schwartz kupfer_ Probably CuO from *Black copper
oxidation of
other minerals
In addition to the above the Author uses the following, which were in
the main artificial products:
_Aerugo_ _Gruenspan oder Verdigris Verdigris
Spanschgruen_
_Aes luteum_ _Gelfarkupfer_ } Impure blister { Unrefined copper
} copper { (see note 16,
} { p. 511)
_Aes caldarium_ _Lebeterkupfer_ } {
_Aeris flos_ _Kupferbraun_ } Cupric oxide { Copper flower
} scales {
} {
_Aeris squama_ _Kupferhammer- } { Copper scale (see
schlag_ } { note 9, p. 233)
_Atramentum _Blaw kupfer Chalcanthite Native blue
sutorium wasser_ vitriol (see
caeruleum_ or note on p. 572)
_chalcanthum_
Blue and green copper minerals were distinguished by all the ancient
mineralogists. Theophrastus, Dioscorides, Pliny, etc., all give
sufficient detail to identify their _cyanus_ and _caeruleum_ partly with
modern azurite, and their _chrysocolla_ partly with the modern mineral
of the same name. However, these terms were also used for vegetable
pigments, as well as for the pigments made from the minerals. The Greek
origin of _chrysocolla_ (_chrysos_, gold and _kolla_, solder) may be
blamed with another and distinct line of confusion, in that this term
has been applied to soldering materials, from Greek down to modern
times, some of the ancient mineralogists even asserting that the copper
mineral _chrysocolla_ was used for this purpose. Agricola uses
_chrysocolla_ for borax, but is careful to state in every case (see note
xx., p. x): "_Chrysocolla_ made from _nitrum_," or "_Chrysocolla_ which
the Moors call Borax." Dioscorides and Pliny mention substances which
were evidently copper sulphides, but no description occurs prior to
Agricola that permits a hazard as to different species.
LEAD MINERALS.
_Plumbarius lapis_ _Glantz_ Galena Galena
_Galena_ _Glantz und Galena Galena
pleiertz_
_Plumbum nigrum } _Pleiertz oder Cerussite Yellow lead ore
lutei coloris_ } pleischweis_ (PbCO_{3})
}
_Plumbago }
metallica_ }
_Cerussa_ _Pleiweis_ Artificial White-lead (see
White-lead note 4, p. 440)
_Ochra facticia_ _Pleigeel_ Massicot (Pb O) *Lead-ochre (see
or _ochra note 8, p. 232)
plumbaria_
_Molybdaena_ } _Herdplei_ Part litharge Hearth-lead (see
} note 37, p. 476)
_Plumbago }
fornacis_ }
_Spuma argenti_ } _Glett_ Litharge Litharge (see note
} on p. 465)
_Lithargyrum_ }
_Minium _Menning_ Minium Red-lead (see note
secundarium_ (Pb_{3}O_{4}) 7, p. 232)
So far as we can determine, all of these except the first three were
believed by Agricola to be artificial products. Of the first three,
galena is certain enough, but while he obviously was familiar with the
alteration lead products, his descriptions are inadequate and much
confused with the artificial oxides. Great confusion arises in the
ancient mineralogies over the terms _molybdaena_, _plumbago_, _plumbum_,
_galena_, and _spuma argenti_, all of which, from Roman mineralogists
down to a century after Agricola, were used for lead in some form.
Further discussion of such confusion will be found in note 37, p. 476.
Agricola in _Bermannus_ and _De Natura Fossilium_, devotes pages to
endeavouring to reconcile the ancient usages of these terms, and all the
confusion existing in Agricola's time was thrice confounded when the
names _molybdaena_ and _plumbago_ were assigned to non-lead minerals.
TIN. Agricola knew only one tin mineral: _Lapilli nigri ex quibus
conflatur plumbum candidum_, _i.e._, "Little black stones from which tin
is smelted," and he gives the German equivalent as _zwitter_,
"tin-stone." He describes them as being of different colours, but
probably due to external causes.
ANTIMONY. (_Interpretatio_,--_spiesglas_.) The _stibi_ or _stibium_ of
Agricola was no doubt the sulphide, and he follows Dioscorides in
dividing it into male and female species. This distinction, however, is
impossible to apply from the inadequate descriptions given. The mineral
and metal known to Agricola and his predecessors was almost always the
sulphide, and we have not felt justified in using the term antimony
alone, as that implies the refined product, therefore, we have adopted
either the Latin term or the old English term "grey antimony." The
smelted antimony of commerce sold under the latter term was the
sulphide. For further notes see p. 428.
BISMUTH*. _Plumbum cinereum_ (_Interpretatio_,--_bismut_). Agricola
states that this mineral occasionally occurs native, "but more often as
a mineral of another colour" (_De Nat. Fos._, p. 337), and he also
describes its commonest form as black or grey. This, considering his
localities, would indicate the sulphide, although he assigns no special
name to it. Although bismuth is mentioned before Agricola in the
_Nuetzliche Bergbuechlin_, he was the first to describe it (see p. 433).
QUICKSILVER. Apart from native quicksilver, Agricola adequately
describes cinnabar only. The term used by him for the mineral is _minium
nativum_ (_Interpretatio_,--_bergzinober_ or _cinnabaris_). He makes the
curious statement _(De Nat. Fos._ p. 335) that _rudis_ quicksilver also
occurs liver-coloured and blackish,--probably gangue colours. (See p.
432).
ARSENICAL MINERALS. Metallic arsenic was unknown, although it has been
maintained that a substance mentioned by Albertus Magnus (_De Rebus
Metallicis_) was the metallic form. Agricola, who was familiar with all
Albertus's writings, makes no mention of it, and it appears to us that
the statement of Albertus referred only to the oxide from sublimation.
Our word "arsenic" obviously takes root in the Greek for orpiment, which
was also used by Pliny (XXXIV, 56) as _arrhenicum_, and later was
modified to _arsenicum_ by the Alchemists, who applied it to the oxide.
Agricola gives the following in _Bermannus_ (p. 448), who has been
previously discussing realgar and orpiment:--"_Ancon_: Avicenna also has
a white variety. _Bermannus_: I cannot at all believe in a mineral of a
white colour; perhaps he was thinking of an artificial product; there
are two which the Alchemists make, one yellow and the other white, and
they are accounted the most powerful poisons to-day, and are called only
by the name _arsenicum_." In _De Natura Fossilium_ (p. 219) is described
the making of "the white variety" by sublimating orpiment, and also it
is noted that realgar can be made from orpiment by heating the latter
for five hours in a sealed crucible. In _De Re Metallica_ (Book X.), he
refers to _auripigmentum facticum_, and no doubt means the realgar made
from orpiment. The four minerals of arsenic base mentioned by Agricola
were:--
_Auripigmentum_ _Operment_ Orpiment Orpiment
(As_{2}S_{3})
_Sandaraca_ _Rosgeel_ Realgar (As S) Realgar
_Arsenicum_ _Arsenik_ Artificial White arsenic
arsenical oxide
_Lapis subrutilus _Mistpuckel_ Arsenopyrite *Mispickel
atque ... (Fe As S)
splendens_
We are somewhat uncertain as to the identification of the last. The
yellow and red sulphides, however, were well known to the Ancients, and
are described by Aristotle, Theophrastus (71 and 89), Dioscorides (V,
81), Pliny (XXXIII, 22, etc.); and Strabo (XII, 3, 40) mentions a mine
of them near Pompeiopolis, where, because of its poisonous character
none but slaves were employed. The Ancients believed that the yellow
sulphide contained gold--hence the name _auripigmentum_, and Pliny
describes the attempt of the Emperor Caligula to extract the gold from
it, and states that he did obtain a small amount, but unprofitably. So
late a mineralogist as Hill (1750) held this view, which seemed to be
general. Both realgar and orpiment were important for pigments,
medicinal purposes, and poisons among the Ancients. In addition to the
above, some arsenic-cobalt minerals are included under _cadmia_.
IRON MINERALS.
_Ferrum purum_ _Gedigen eisen_ Native iron *Native iron
_Terra ferria_ _Eisen ertz_ } Various soft and } Ironstone
} hard iron }
_Ferri vena_ _Eisen ertz_ } ores, probably }
} mostly hematite}
_Galenae genus _Eisen glantz_ } }
tertium omnis } }
metalli } }
inanissimi_ } }
} }
_Schistos_ _Glaskoepfe oder } }
bluetstein_ } }
} }
_Ferri vena _Leber ertz_ } }
jecoris colore_ } }
_Ferrugo_ _Ruest_ Part limonite Iron rust
_Magnes_ _Siegelstein Magnetite Lodestone
oder magnet_
_Ochra nativa_ _Berg geel_ Limonite Yellow ochre or
ironstone
_Haematites_ _Bluet stein_ { Part hematite Bloodstone or
{ Part jasper ironstone
_Schistos_ _Glas koepfe_ Part limonite Ironstone
_Pyrites_ _Kis_ Pyrites Pyrites
_Pyrites argenti _wasser oder Marcasite *White iron
coloris_ weisser kis_ pyrites
_Misy_ _Gel atrament_ Part copiapite _Misy_ (see note
on p. 573)
_Sory_ _Graw und Partly a _Sory_ (see note
schwartz decomposed iron on p. 573)
atrament_ pyrite
_Melanteria_ _Schwartz und Melanterite _Melanteria_ (see
grau atrament_ (native vitriol) note on p. 573)
The classification of iron ores on the basis of exterior
characteristics, chiefly hardness and brilliancy, does not justify a
more narrow rendering than "ironstone." Agricola (_De Nat. Fos._, Book
V.) gives elaborate descriptions of various iron ores, but the
descriptions under any special name would cover many actual minerals.
The subject of pyrites is a most confused one; the term originates from
the Greek word for fire, and referred in Greek and Roman times to almost
any stone that would strike sparks. By Agricola it was a generic term in
somewhat the same sense that it is still used in mineralogy, as, for
instance, iron pyrite, copper pyrite, etc. So much was this the case
later on, that Henckel, the leading mineralogist of the 18th Century,
entitled his large volume _Pyritologia_, and in it embraces practically
all the sulphide minerals then known. The term _marcasite_, of mediaeval
Arabic origin, seems to have had some vogue prior and subsequent to
Agricola. He, however, puts it on one side as merely a synonym for
pyrite, nor can it be satisfactorily defined in much better terms.
Agricola apparently did not recognise the iron base of pyrites, for he
says (_De Nat. Fos._, p. 366): "Sometimes, however, pyrites do not
contain any gold, silver, copper, or lead, and yet it is not a pure
stone, but a compound, and consists of stone and a substance which is
somewhat metallic, which is a species of its own." Many varieties were
known to him and described, partly by their other metal association, but
chiefly by their colour.
CADMIA. The minerals embraced under this term by the old mineralogists
form one of the most difficult chapters in the history of mineralogy.
These complexities reached their height with Agricola, for at this time
various new minerals classed under this heading had come under debate.
All these minerals were later found to be forms of zinc, cobalt, or
arsenic, and some of these minerals were in use long prior to Agricola.
From Greek and Roman times down to long after Agricola, brass was made
by cementing zinc ore with copper. Aristotle and Strabo mention an earth
used to colour copper, but give no details. It is difficult to say what
zinc mineral the _cadmium_ of Dioscorides (V, 46) and Pliny (XXXIV, 2),
really was. It was possibly only furnace calamine, or perhaps blende for
it was associated with copper. They amply describe _cadmia_ produced in
copper furnaces, and _pompholyx_ (zinc oxide). It was apparently not
until Theophilus (1150) that the term _calamina_ appears for that
mineral. Precisely when the term "zinc," and a knowledge of the metal,
first appeared in Europe is a matter of some doubt; it has been
attributed to Paracelsus, a contemporary of Agricola (see note on p.
409), but we do not believe that author's work in question was printed
until long after. The quotations from Agricola given below, in which
_zincum_ is mentioned in an obscure way, do not appear in the first
editions of these works, but only in the revised edition of 1559. In
other words, Agricola himself only learned of a substance under this
name a short period before his death in 1555. The metal was imported
into Europe from China prior to this time. He however does describe
actual metallic zinc under the term _conterfei_, and mentions its
occurrence in the cracks of furnace walls. (See also notes on p. 409).
The word cobalt (German _kobelt_) is from the Greek word _cobalos_,
"mime," and its German form was the term for gnomes and goblins. It
appears that the German miners, finding a material (Agricola's
"corrosive material") which injured their hands and feet, connected it
with the goblins, or used the term as an epithet, and finally it became
established for certain minerals (see note 21, p. 214, on this subject).
The first written appearance of the term in connection with minerals,
appears in Agricola's _Bermannus_ (1530). The first practical use of
cobalt was in the form of _zaffre_ or cobalt blue. There seems to be no
mention of the substance by the Greek or Roman writers, although
analyses of old colourings show some traces of cobalt, but whether
accidental or not is undetermined. The first mention we know of, was by
Biringuccio in 1540 (_De La Pirotechnia_, Book II, Chap. IX.), who did
not connect it with the minerals then called _cobalt_ or _cadmia_.
"_Zaffera_ is another mineral substance, like a metal of middle weight,
which will not melt alone, but accompanied by vitreous substances it
melts into an azure colour so that those who colour glass, or paint
vases or glazed earthenware, make use of it. Not only does it serve for
the above-mentioned operations, but if one uses too great a quantity of
it, it will be black and all other colours, according to the quantity
used." Agricola, although he does not use the word _zaffre_, does refer
to a substance of this kind, and in any event also missed the relation
between _zaffre_ and cobalt, as he seems to think (_De Nat. Fos._, p.
347) that _zaffre_ came from bismuth, a belief that existed until long
after his time. The cobalt of the Erzgebirge was of course, intimately
associated with this mineral. He says, "the slag of bismuth, mixed
together with metalliferous substances, which when melted make a kind of
glass, will tint glass and earthenware vessels blue." _Zaffre_ is the
roasted mineral ground with sand, while _smalt_, a term used more
frequently, is the fused mixture with sand.
The following are the substances mentioned by Agricola, which, we
believe, relate to cobalt and zinc minerals, some of them arsenical
compounds. Other arsenical minerals we give above.
_Cadmia fossilis_ _Calmei_; _lapis Calamine Calamine
calaminaris_
_Cadmia metallica_ _Kobelt_ Part cobalt *_Cadmia
metallica_
_Cadmia fornacis_ _Mitlere und Furnace Furnace accretions
obere accretions or
offenbrueche_ furnace calamine
_Bituminosa _Kobelt des (Mannsfeld copper _Bituminosa cadmia_
cadmia_ bergwacht_ schists) (see note 4,
p. 273)
_Galena inanis_ _Blende_ Sphalerite* *Blende
(Zn S)
_Cobaltum -- Smallite* } _Cadmia metallica_
cineraceum_ (CoAs_{2}) }
}
_Cobaltum nigrum_ -- Abolite* }
}
_Cobaltum ferri -- Cobaltite }
colore_ (CoAsS) }
_Zincum_ _Zinck_ Zinc Zinc
_Liquor Candidus _Conterfei_ Zinc See note 48, p. 408
ex fornace ...
etc._
_Atramentum -- Goslarite *Native white
sutorium, (Zn SO_{4}) vitriol
candidum, potissimum
reperitur Goselariae_
_Spodos _Geeler zechen } Either natural { Grey _spodos_
subterranea rauch_ } or artificial {
cinerea_ } zinc oxides, {
} no doubt {
_Spodos _Schwartzer } containing { Black _spodos_
subterranea zechen rauch, } arsenical {
nigra_ auff dem } oxides {
Altenberge } {
nennet man in } {
kis_ } {
} {
_Spodos _Grauer zechen } { Green _spodos_
subterranea rauch_ } {
viridis_ } {
} {
_Pompholyx_ _Huettenrauch_ } { _Pompholyx_ (see
} { note 26, p. 394)
As seen from the following quotations from Agricola, on _cadmia_ and
cobalt, there was infinite confusion as to the zinc, cobalt, and arsenic
minerals; nor do we think any good purpose is served by adding to the
already lengthy discussion of these passages, the obscurity of which is
natural to the state of knowledge; but we reproduce them as giving a
fairly clear idea of the amount of confusion then existing. It is,
however, desirable to bear in mind that the mines familiar to Agricola
abounded in complex mixtures of cobalt, nickel, arsenic, bismuth, zinc,
and antimony. Agricola frequently mentions the garlic odour from _cadmia
metallica_, which, together with the corrosive qualities mentioned
below, would obviously be due to arsenic. _Bermannus_ (p. 459). "This
kind of pyrites miners call _cobaltum_, if it be allowed to me to use
our German name. The Greeks call it _cadmia_. The juices, however, out
of which pyrites and silver are formed, appear to solidify into one
body, and thus is produced what they call _cobaltum_. There are some who
consider this the same as pyrites, because it is almost the same. There
are some who distinguish it as a species, which pleases me, for it has
the distinctive property of being extremely corrosive, so that it
consumes the hands and feet of the workmen, unless they are well
protected, which I do not believe that pyrites can do. Three kinds are
found, and distinguished more by the colour than by other properties;
they are black (abolite?), grey (smallite?), and iron colour (cobalt
glance?). Moreover, it contains more silver than does pyrites...."
_Bermannus_ (p. 431). "It (a sort of pyrites) is so like the colour of
galena that not without cause might anybody have doubt in deciding
whether it be pyrites or galena.... Perhaps this kind is neither pyrites
nor galena, but has a genus of its own. For it has not the colour of
pyrites, nor the hardness. It is almost the colour of galena, but of
entirely different components. From it there is made gold and silver,
and a great quantity is dug out from Reichenstein which is in Silesia,
as was lately reported to me. Much more is found at Raurici, which they
call _zincum_; which species differs from pyrites, for the latter
contains more silver than gold, the former only gold, or hardly any
silver."
(_De Natura Fossilium_, p. 170). "_Cadmia fossilis_ has an odour like
garlic" ... (p. 367). "We now proceed with _cadmia_, not the _cadmia
fornacis_ (furnace accretions) of which I spoke in the last book, nor
the _cadmia fossilis_ (calamine) devoid of metal, which is used to
colour copper, whose nature I explained in Book V, but the metallic
mineral (_fossilis metallica_), which Pliny states to be an ore from
which copper is made. The Ancients have left no record that another
metal could be smelted from it. Yet it is a fact that not only copper
but also silver may be smelted from it, and indeed occasionally both
copper and silver together. Sometimes, as is the case with pyrites, it
is entirely devoid of metal. It is frequently found in copper mines, but
more frequently still in silver mines. And there are likewise veins of
_cadmia_ itself.... There are several species of the _cadmia fossilis_
just as there were of _cadmia fornacum_. For one kind has the form of
grapes and another of broken tiles, a third seems to consist of layers.
But the _cadmia fossilis_ has much stronger properties than that which
is produced in the furnaces. Indeed, it often possesses such highly
corrosive power that it corrodes the hands and feet of the miners. It,
therefore, differs from pyrites in colour and properties. For pyrites,
if it does not contain vitriol, is generally either of a gold or silver
colour, rarely of any other. _Cadmia_ is either black or brown or grey,
or else reddish like copper when melted in the furnace.... For this
_cadmia_ is put in a suitable vessel, in the same way as quicksilver, so
that the heat of the fire will cause it to sublimate, and from it is
made a black or brown or grey body which the Alchemists call 'sublimated
_cadmia_' (_cadmiam sublimatam_). This possesses corrosive properties of
the highest degree. Cognate with _cadmia_ and pyrites is a compound
which the Noricians and Rhetians call _zincum_. This contains gold and
silver, and is either red or white. It is likewise found in the Sudetian
mountains, and is devoid of those metals.... With this _cadmia_ is
naturally related mineral _spodos_, known to the Moor Serapion, but
unknown to the Greeks; and also _pompholyx_--for both are produced by
fire where the miners, breaking the hard rocks in drifts, tunnels, and
shafts, burn the _cadmia_ or pyrites or galena or other similar
minerals. From _cadmia_ is made black, brown, and grey _spodos_; from
pyrites, white _pompholyx_ and _spodos_; from galena is made yellow or
grey _spodos_. But _pompholyx_ produced from copper stone (_lapide
aeroso_) after some time becomes green. The black _spodos_, similar to
soot, is found at Altenberg in Meissen. The white _pompholyx_, like wool
which floats in the air in summer, is found in Hildesheim in the seams
in the rocks of almost all quarries except in the sandstone. But the
grey and the brown and the yellow _pompholyx_ are found in those silver
mines where the miners break up the rocks by fire. All consist of very
fine particles which are very light, but the lightest of all is white
_pompholyx_."
QUARTZ MINERALS.
_Quarzum_ ("which _Quertz oder Quartz Quartz (see note
Latins call kiselstein_ 15, p. 380)
_silex_")
_Silex_ _Hornstein oder Flinty or jaspery Hornstone
feurstein_ quartz
_Crystallum_ _Crystal_ Clear crystals Crystal
_Achates_ _Achat_ Agate Agate
_Sarda_ _Carneol_ Carnelian Carnelian
_Jaspis_ _Jaspis_ Part coloured _Jaspis_
quartz, part
jade
_Murrhina_ _Chalcedonius_ Chalcedony Chalcedony
_Coticula_ _Goldstein_ A black silicious Touchstone (see
stone note 37, p. 252)
_Amethystus_ _Amethyst_ Amethyst Amethyst
LIME MINERALS.
_Lapis } _Gips_ Gypsum Gypsum
specularis_ }
}
_Gypsum_ }
_Marmor_ _Marmelstein_ Marble Marble
_Marmor _Alabaster_ Alabaster Alabaster
alabastrites_
_Marmor glarea_ -- Calcite (?) Calc spar(?)
_Saxum calcis_ _Kalchstein_ Limestone Limestone
_Marga_ _Mergel_ Marl Marl
_Tophus_ _Toffstein oder Sintry _Tophus_ (see note
topstein_ limestones, 13, p. 233)
stalagmites,
etc.
MISCELLANEOUS.
_Amiantus_ _Federwis, pliant Usually asbestos Asbestos
salamanderhar_
_Magnetis_ _Silberweis oder } Mica *Mica
katzensilber_ }
}
_Bracteolae -- }
magnetidi simile_ }
}
_Mica_ _Katzensilber }
oder glimmer_ }
_Silex ex eo ictu -- Feldspar *Feldspar
ferri facile
ignis
elicitur....
excubus figuris_
_Medulla saxorum_ _Steinmarck_ Kaolinite Porcelain clay
_Fluores (lapides _Flusse_ Fluorspar *Fluorspar
gemmarum simili)_ (see note 15,
p. 380)
_Marmor in _Spat_ Barite *Heavy spar
metallis
repertum_
Apart from the above, many other minerals are mentioned in other
chapters, and some information is given with regard to them in the
footnotes.
[9] Three _librae_ of silver per _centumpondium_ would be equal to 875
ounces per short ton.
[10] As stated in note on p. 2, Agricola divided "stones so called" into
four kinds; the first, common stones in which he included lodestone and
jasper or bloodstone; the second embraced gems; the third were
decorative stones, such as marble, porphyry, etc.; the fourth were
rocks, such as sandstone and limestone.
LODESTONE. (_Magnes_; _Interpretatio_ gives _Siegelstein oder magnet_).
The lodestone was well-known to the Ancients under various
names--_magnes_, _magnetis_, _heraclion_, and _sideritis_. A review of
the ancient opinions as to its miraculous properties would require more
space than can be afforded. It is mentioned by many Greek writers,
including Hippocrates (460-372 B.C.) and Aristotle; while Theophrastus
(53), Dioscorides (V, 105), and Pliny (XXXIV, 42, XXXVI, 25) describe it
at length. The Ancients also maintained the existence of a stone,
_theamedes_, having repellant properties, and the two were supposed to
exist at times in the same stone.
EMERY. (_Smiris_; _Interpretatio_ gives _smirgel_). Agricola (_De Natura
Fossilium_, p. 265) says: "The ring-makers polish and clean their hard
gems with _smiris_. The glaziers use it to cut their glass into sheets.
It is found in the silver mines of Annaberg in Meissen and elsewhere."
Stones used for polishing gems are noted by the ancient authors, and
Dana (Syst. of Mineralogy, p. 211) considers the stone of Armenia, of
Theophrastus (77), to be emery, although it could quite well be any hard
stone, such as Novaculite--which is found in Armenia. Dioscorides (V,
166) describes a stone with which the engravers polish gems.
LAPIS JUDAICUS. (_Interpretatio_ gives _Jueden stein_). This was
undoubtedly a fossil, possibly a _pentremites_. Agricola (_De Natura
Fossilium_, p. 256) says: "It is shaped like an acorn, from the obtuse
end to the point proceed raised lines, all equidistant, etc." Many
fossils were included among the semi-precious stones by the Ancients.
Pliny (XXXVII, 55, 66, 73) describes many such stones, among them the
_balanites_, _phoenicitis_ and the _pyren_, which resemble the above.
TROCHITIS. (_Interpretatio_ gives _spangen oder rederstein_). This was
also a fossil, probably crinoid stems. Agricola (_De Natura Fossilium_,
p. 256) describes it: "_Trochites_ is so called from a wheel, and is
related to _lapis judaicus_. Nature has indeed given it the shape of a
drum (_tympanum_). The round part is smooth, but on both ends as it were
there is a module from which on all sides there extend radii to the
outer edge, which corresponds with the radii. These radii are so much
raised that it is fluted. The size of these _trochites_ varies greatly,
for the smallest is so little that the largest is ten times as big, and
the largest are a digit in length by a third of a digit in thickness ...
when immersed in vinegar they make bubbles."
[11] The "extraordinary earths" of Agricola were such substances as
ochres, tripoli, fullers earth, potters' clay, clay used for medicinal
purposes, etc., etc.
[12] Presumably the ore-body dips into a neighbouring property.
[13] The various kinds of iron tools are described in great detail in