When a man of observation walks over the Gold Fields, his attention is
arrested by the following facts.
1. The prevalent rocks are observed to be of a crystalline, or what is
called igneous, character; as, granites of all varieties, quartz, mica,
slate, felspar, sienite &c. Some felspar is seen decomposed into a soft
white finger-staining mineral, or into fine porcelain clay. At the “Gap”
of the river Macquarie the sienite is flanked by precipitous silicious
slates. The Mount Alexander range is of a granitic character, and the
beds of the streams running from it, on the Bendigo road, are filled
with huge boulders of granite on a granite floor, containing parallel
veins of crystallized felspar, having usually a north and south
direction. No detritus of other rocks is found on the granite by the
“Porcupine.” Some of the rocks bear fantastic resemblance to Beehives,
Logan stones, and Scandinavian Tumuli. Granite is the bed of the
Macquarie at Bathurst, and the base of the Mullion range, near which
were the first diggings of New South Wales. The quartz is of all kinds;
black, white, yellow, pink, green, red, spotted, streaked, mosaic,
porous, fibrous, clinker like, and crystallized. Carbon makes it black;
copper or chlorine, green; oxide of iron, red or brown; manganese, rose
colour. The crystals are hexaedron pyramids, single or double, of
different sizes and degrees of transparency. Some rise from the surface
like wedges, having a singular appearance. The prisms are triangular,
quadrilateral or pentagonal; some crystals have others attached to their
sides. Veins of black quartz are observed with the centre very
vesicular. Carious quartz, or swimming stone, is not common. The
granulated quartz or grindstone schist has often minute transparent
crystals in cavities. From a hole in Golden Gully, Bendigo, I obtained a
specimen of soft sandstone, with most exquisitely beautiful veins of
crystallized quartz running in all directions.
2. The Crystalline rocks are observed gradually changing into what is
called the Sedimentary rocks, as slates. Such a transition from the
crystalline to the laminated form is by insensible degrees. The
experience of the miner is often opposed to the theories of geologists.
He cannot help noticing the different kinds of slates, as presenting
proof of their being transmutations of, or some among the many kinds of
developement in, crystalline rocks. There are slates as amorphous
looking as any Huttonian can desire. Others are so silicious, as to be
denominated by the New South Wales geologists, _Quartzites_. On the
Bell’s creek the clay slate changes into jasper. The chlorite slate of
Ophir is so full of quartz veins, and dykes and bosses of quartz, as to
be called by Sir T. L. Mitchell, _Quartz iferons schist_. Instances are
numerous of slate with embedded quartz, and quartz entangling slate. At
the cathedral rock, near Specimen Hill, Bendigo, numerous veins of
chlorite slate are seen running unharmed and unchanged amidst that huge
block of so called, igneous rock. The same specimen of quartz has
exhibited in different parts not only different colours, but the
clinker, the calcined, and the transparent conditions. The Rev. W. B.
Clarke, of Sydney, hints at the probability of quartz, greenstone,
basalt, and slates, by the influence of segregation, chemical affinity,
galvanic or other forces, being “derived from the same original source,
and indefinitely varied in the order of their arrangements and relations
to each other at different intervals.” Mr. Clarke’s observations on the
Diggings’ ground, would seem rather to have confounded his geological
creed. The absence of ordinary stratification, even in the holes, is a
remarkable feature. The character of stuff through which we have to go
on the tops of hills resembles that in the gullies. Though much of the
soil bears evidence of diluvial action, yet a considerable portion
clearly results from the decomposition of the rocks near. The great
irregularity of mineral beds in the holes, no two holes being alike,
would not present the idea of gentle depositions, nor are we warranted
to assume volcanic dislocation. Such fantastic changes in the order and
depths of these mineral beds, were compared by a diggings’ friend to the
alternations of the eight notes of music in different bars.
Our slates in Victoria are elongated, amorphous, crystalline, contorted,
laminated, with or without cleavage, red, brown, white, blue, and
chocolate color. Some are very talcose and soapy. In others grains or
streaks like rainbows are seen. Mundic or Iron pyrites’ crystals are
found in dark, friable, unctious slate of Forest creek. At Miles’ creek,
Bendigo, are fine curvillinial lines in red slates. Near the old square,
Forest creek, and beside Fryer’s creek is some splendid blue book slate,
resembling the leaves of a book. The cleavage of the slates is evidently
made by magnetic agency. Sometimes, as at Bendigo, the cleavage planes
preserve a true parallelism while passing through contorted hard slate.
3. The rocks of the diggings are observed in successive bands of various
colors and compositions with a great vertical inclination. This is the
same as in other gold countries. Intelligent miners are much struck with
this fact of rock succeeding rock over a country side by side, and all
with a perpendicular direction. The slate has some odd changes of
position, influenced doubtless by local disturbances. On the road from
Bendigo to Bullock creek, the rock may be seen in one place dipping 80°
to the east, a little further 80° to the west, then 10° to the west, &c.
In Iron bark gully I noticed in a square yard of space the following
different position, in some blue roofing slate; 45° to N E, 30° to Es
70° to N. The Pipe clay, which, being silicate of alumina, is decomposed
from siliceous slates and granites, has, like the neighbouring rocks,
this same vertical inclination.
4. The ridges of rocks are observed to run nearly in a North and South
direction. This is the same as in all gold countries, and establishes
the theory of terrestrial magnetic agency.
5. There is a remarkable abundance of iron. Crystals of iron pyrites are
common. The carburet of iron or emery, like iron sand, is always
associated with gold. Oxydulous masses of iron form a precipitous
waterfall of 60 feet near Oaky Creek, New South Wales. Ferruginous, or
iron bearing, conglomerate, overhangs the river at Ophir. Auriferous
bands of argillaceous iron ore traverse the limestone of Bungonia. Large
nodules of peroxide of iron, and magnetic iron ore of all kinds, are
taken out of our Victoria Diggings. The burnt stuff, or burnt quartz of
the miners, is a ferruginous cement binding quartz pebbles. There is no
need of referring this compound to volcanic or electric fire. Chemical
action with moisture will make any mixture hard enough. Roman cement
when dried is not very soft. In the Ballarat holes the “Burnt Quartz”
has been found ten feet thick; it is less at the Mount, and less still
at Bendigo, though on some Bendigo hills it occurs six or eight feet.
6. The Gold is found in positions where there is a transition from the
ordinary crystalline rocks to those of the sedimentary character. This
remark leads us at once to the interesting and debated subject of the
“ORIGIN OF GOLD.” Some say that the gold of our gullies and hills is
washed down from a matrix or source,—that is from certain golden lodes
in a mountain. Others affirm that a volcano once burst forth and
showered gold instead of cinders, and they direct us to the shot like
appearance of nuggets. It is believed, also, that mica is the mother of
Gold. Without doubt some is washed down by rivers, and more was
deposited by ancient floods when covering the whole country, but a large
amount is found _in situ_ as it always had been. It is assuredly a fact
noticed in all auriferous countries, that the gold is seen in positions
where the sedimentary looking rocks come in contact with the so called
igneous rocks. It is also, always found associated with iron, and
commonly in the decomposition of rocks. It is in auriferous sulphuret of
iron in Chili; ochreous decomposed silicious rock, adhering to specular
iron, in Columbia; ferruginous sands in the Niger; decomposed reddish
granite in Thibet; honeycomb quartz and rotten slate in Virginia; black
peroxide of iron in Ceylon; pyrites in decomposed felspar in Hungary;
sulphuret of iron in quartz in France; ferruginous clay slate in
Granada; with iron of all kinds in Wieklow; decomposed crystalline rock
with iron pyrites in the Ural; so in California, so in Australia. It
would appear, then, that the gold was the produce of certain changes in
certain rocks. The formation of crystals is somewhat analogous. The wall
of a mine previously bare is seen gradually to get covered with
crystals. Even crystals of iron pyrites are so produced, and are known
by miners as “Young Mundic.” There must be, then, constant activity
going on in the apparently inert mass of mineral matter. There is no
rest in creation. The heavens above us speak of eternal movement. The
animal and vegetable kingdoms reveal an incessant round of change. And
now the dull rock unfolds to us the existence of motions and
transformations that know no stay. There may be death upon the earth,
there can be none beneath. We sweep off crystals only to make way for
more. And may it not be so with metals in general? We may not know the
particular elements and circumstances necessary for the formation of the
yellow treasure, but some approximate conception may be gained by
observation.
If crystals are the flowers of the earth beneath, metals are
unquestionably mineral trees in gradual development, and dependent upon
certain acids, alkalies, and other materials, for sources of their
transformations. Moisture seems essential for these chemical changes.
The production of gold is observed to take place chiefly towards the
surface, though at a considerable depth in the compact rock very minute
particles may be detected. When the crystalline rock disintegrates, iron
sand is developed and accumulated. Mr. Hopkins, of the Port Phillip Gold
Company, the ablest practical mining geologist of the day, and who calls
clay slate “_oxidated crust of granite_,” observes, that it is “within
the limits of this transition of the crystalline base into the oxydated
compound that the minerals become principally developed in veins, &c.”
An interesting illustration of this is afforded at Specimen Hill,
Bendigo, where the metal lies between the quartz and the slate. Again,
at Clunes, the fissures in the quartz are filled with greasy red earth,
highly impregnated with iron, and in this was the gold. Sir T. L.
Mitchell, in his most interesting report, tells us, that the gold of
Summerhill Creek was “in incrementitious portions and separate
increments of quartzose crystals.” In fact, the metal is often detected
in considerable masses in the solid rock apart from any veins, which
could not be, unless formed in the very place. It is not often, however,
that a lump of 106lbs, as at Louisa Creek, is found thus detached.
Our Gold deposits of Victoria, then, are not the products of washings
from distant rocks, but of certain friable metalliferous rocks, which
gradually wearing away unfold their treasures; and the gold itself is a
sort of crystallization or growth in ferruginous crystalline formations,
acting under regular, though at present unknown laws. _Our rocks are at
this moment producing gold._ The metal is found on the tops of hills and
in all possible situations. We never are sure where to drop on it. All
we see is that _where it is, there it is_. In some gullies the sides of
the hills are not favorable; in others they are. Long Gully, Bendigo,
received a return of visitors, after being _wrought out_, to have the
hills ransacked. Then, with regard to the Pipe clay, the gold is in it,
on it, or under it, according to the locality; that is, according to the
period when the metal was formed, and rolled off from the parent rock,
whether before, or after, or during the development of the decomposed
felspar. Some men who came down to pipe clay in a certain gully found no
gold, and retired. Another party pierced through the white floor, and
brought up the wealth. In Californian gully more than six feet of it
contained gold. The pipe clay varies much in depth, from an inch to
forty feet. Occasionally, as in the shallow, lucky, holes of Peg Leg
Gully, there is no pipe clay at all. The character of the gold changes
according to the locality in which the transmuting agency has been more
or less active. The lumps, however, are not larger in proportion to
proximity to some matrix, as supposed, or when nearer to the volcano,
which others think threw out the lovely, weighty, cinders.
Notwithstanding all this uncertainty which exists as to the whereabouts
of gold, I believe that with the progress of science it will be quite
possible at once to know the precise place in which to discover the
hidden beauties. O the delicious yellow crystals! Who does not love to
view them, whether in the form of fibres, scales, or nuggets! The poet
well may sing;
Or 'midst the darksome wonders
Which earth’s vast caves conceal,
Where subterranean thunders
The miner’s path reveal;
Where bright in matchless lustre,
The lithal flowers (_crystals_) unfold,
And 'midst the beauteous cluster,
Beams efflorescent Gold.
[ADVERTISEMENT.]