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Calcedony

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CALCEDONY.
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white ; when broken, the interior has a pearly reflec­tion, slightly translucent at the sharp edges. Harder than the opal, this substance takes a good polish ; it is unaltered under the action of the blow-pipe, and its specific weight is 2'2.
The cacholong is found in separate bits in the rivers of Bokhara, in the Feròe Islands, in Iceland, in trapp rocks, and in Greenland. It is also procured in France ; and in Champigny, near Paris, it is brought from the caves of calcareous breccia, and some of it is hard, of bright cleavage, whilst others are light, rough to the touch of the tongue, and soft as chalk, and therefore of inferior quality, and to be regarded as imperfectly formed.
There is a variety of this stone called striped, coming from Feròe and Ireland, which being composed of thin strata of white and opaque opals over strata of cal-cedony, often bluish or greenish, makes very fine cameos. Italian artists call it French stone.
XVIII.
CALCEDONY.
This hard stone is thus named from the province of Calcedony, in Asia Minor, whence, in ancient times, it was procured in great quantities. It is a variety of agate quartz, generally of a milky-white colour, some­times bluish ; and this last tint somewhat increases its value.
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Cacholong Page of 243 Calcedony
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