|
LABRADORITE AND OTHER GEMS. 341
|
||
|
|
||
|
hardly be classed with precious stones, yet it was extensively
used for engraving by the ancients, the Island of Elba affording beautiful crystals of this mineral in Ovid's time, as it does at the present day. It is so generally diffused that it is needless to specify any localities in which it is found. Diaspore. —The name of this mineral signifies " to scatter,"
given on account of its tendency to decrepitate before the blowpipe. It is translucent, with a hardness of six to seven, and embraces quite a variety of colors — greenish, yellowish, brown, gray, and white; some crystals are violet blue when examined in a certain direction, reddish blue in another, and green in a third. Its constituents are alumina and water, with a small per cent of iron and silica ; it bears a resemblance to topaz, and might be used as a gem-stone. It is found in several foreign localities, and in Massachusetts and Pennsylvania. Aiidalusite, chiastolite, or macie, is sometimes called " crossstone," from the figure of a perfect cross which some specimens
afford when cut transversely, of a different color from the rest of the stone, which is usually rose, violet, gray, whitish, brownish, or greenish.. It affords an almost infinite variety of markings, which render this mineral a beautiful ornamental stone. It was called andalusite from Andalusia, in Spain, where it was first discovered, chiastolite from the Greek letter χ {cht), and macie from a Latin word signifying a spot. It is found in several foreign localities, and, as a native mineral, in Maine, Massachusetts, Pennsylvania, and California. Octahedrite. — Crystals of this species, from Brazil, of a
beautiful blue color, are of such remarkable brilliancy as to be often mistaken for diamonds ; those of inferior quality have been found in North Carolina and Rhode Island. It exhibits shades of brown, passing into deep blue or black, and is of sufficient hardness to admit a good polish. |
||
|
|
||