entrance halls of large public buildings or private mansions, and the
Cornwall porphyry is particularly celebrated-for its various tints of
colors. The author distinctly recollects four slabs: one was a black
slab; another, red; a third, green; and a fourth, a large slab,
containing twenty-four specimens of various variegated rocks of
porphyry. Also, the elvan-stone, from the quarries of New Quay, in
Cornwall, which is a beautiful porphyry. The large slab, weighing about
eight hundred pounds, was of very fine red color; it was without flaw
Prussia porphyry is abundant, and there were some fine specimens in the
London Exhibition, such- as a table, a small column and tazza; the
latter was a round slab of red color and fine texture, and the tazza
vase and pedestal were of the same material.
From Sweden and Norway a sienitic porphyry, of grayish-red color, was also in the London Exhibition.
porphyry vase in the Berlin Museum, which, according to the author's
recollection, is about eight feet high and six feet in diameter, is
well deserving a place in this treatise, as it is unique of its kind in
rock is composed essentially of felspar and hornblende, and sometimes
contains quartz or mica, or both. When polished, it forms the most
splendid ornamental stone of all rocks; it is very hard ; and its color
and the mode of distribution of the various ingredients, make it very
agreeable to the eye. It much resembles granite, and is often almost
identical with it; but by close inspection it may be distinguished from
the want or addition of the component ingredients.
Professor Hitchcock describes six varieties of sienite: