The northern corner of this parish is situated on granite, resembling
that of Gulval in every respect, except as to one variety abounding in
mica. Much of this stone may be seen in the more ancient houses at
Penzance. The spot, however, from whence this stone was procured, is
no longer known. A difference of opinion is indeed entertained as to
whether it was gotten from blocks near the surface, or from a bed that
has been exhausted; but all are agreed as to the district from whence
it came; and it is universally known by the name of Ludgvan stone. The
property of cleaving evenly into regular blocks, eminently possessed
by this species of granite, makes it valuable for building purposes;
and this property is clearly derived from the even arrangement of the
scale of mica in which it abounds.
Between the granite and the sea-shore a considerable portion of the
schistose rocks is covered by a marsh, and by banks of sand. These
rocks are made up of compact felspar, sometimes nearly pure, at others
intimately united with hornblend or actynolite; they are traversed by
courses or dykes of felspar porphyry, as may be seen on the sea-shore.
[2] Extracted from an “Account of certain Hill Castles, near
the Land’s End in Cornwall,” by William Cotton, Esq. F.S.A.
printed in the Archæologia, vol. XXII. where a plan and
section of Castle-an-Dinas will be found, taken with greater
care than that in Lysons’s Cornwall. In the Gentleman’s
Magazine, LXXII. p. 393, are engravings of two stone weights
found within the inner circle of this fortress. The weight
of one was seventeen pounds and a half; and that of the
other three pounds one ounce.
LUXILIAN, or LUXULIAN.