Avanturine is an opaque, yellow, brown, or red quartz, spangled with
minute scales of mica or some other mineral, and found principally near
Madrid, in Spain. It is also found in France, Scotland, Bavaria, the
Urals, and Styria.
A beautiful imitation of avanturine, called goldstone, is manufactured
of glass into which metal filings are introduced. This goldstone
is superior to avanturine in every point except that of hardness.
Avanturine and its imitation, but largely the latter, are used for the
cheaper kinds of jewelry, and were very popular in the United States
some years ago.