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Ch. 6: Opal

Ch. 6: Opal Page of 515 Ch. 6: Opal Text size:minus plus Restore normal size   Mail page  Print this page
COMMON FELSPAR                                    315
The Ceylon variety ought only to be called Oriental moon­stone, from the peculiarity that it is more uniform, not striated like that from St. Gothard, and having also a brighter lustre; its chatoyant qualities are therefore more prominent.
Sun-stone contains minute scales of mica, and reflects a pinchbeck-brown tint.
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COMMON FELSPAR.
This felspar occurs in crystals, massive, and disseminated ; its fracture is uneven and splintery; is translucent; has a pearly and vitreous lustre; its colors are white, gray, red, yellow, and green, in their various shades, sometimes with a variegated bluish, greenish, or reddish play of colors; its texture is compact, or minutely foliated.
The amazon-stone, or green felspar, is from Siberia; like­wise splendid grass-green felspar has been found in the Uni­ted States, at Southbridge and Hingham, Massachusetts, and Cow Bay, New York; of apple-green color, at Topsham, and near Baltimore, Maryland. Also, the American glassy or vitreous felspar, found in Delaware, which ought prop­erly to be quoted as a distinct species, is arranged with this variety.
Felspar is widely diffused all over the globe, and with a few exceptions is more common than any other mineral; it forms a constituent part of most primitive rocks, such as gneiss, granite, &c.; is the principal ingredient of the sienites, porphyry, and, in fact, with a small percentage of other minerals, forms whole mountain ranges and chains in various parts of the globe: such we see in Siberia, the north and west of Scotland, &c, all of which are surrounded by felspar. Immense beds exist in the United States: around Wilmington, in the State of Delaware, is an inexhaustible deposit of exquisite and perfectly pure felspar; and in
Ch. 6: Opal Page of 515 Ch. 6: Opal
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