for
fire, and was given in allusion to the fact that owing to its hardness
it will strike fire with steel. It is heavy, its specific gravity being
five times that of water. It is quite brittle. It crystallizes in the
isometric system, crystals of cubic or cuboidal forms being the most
common. Owing to its abundance in nature it has practically no
intrinsic value except in large quantities, in which case it forms an
ore of sulphur. When cut into various objects of ornament, however, it
has quite a pleasing effect, and at times has been much in favor. It is
used for ornamenting bracelets, brooches, scarf-pins, and the like, and
in certain forms in rings.
For
these purposes it has usually been artificially facetted, thus
displaying its brilliant luster. An American firm has recently,
however, employed the pyrite found in the form of a coating of small,
bright crystals, nearly uniform in height, for use in jewelry. These
coatings are obtained from beds of anthracite coal, and only require
smoothing on the back and cutting into pieces of suitable size and
shape to be made available.
One
of the drawbacks to the use of pyrite in this way is its easy liability
to tarnish, and the difficulty afterwards of restoring the original
luster. Some groups of crystals will remain bright a long time while
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