Bronzite
is a member of the orthopyroxene group of minerals,
belonging with enstatite and hypersthene to the orthorhombic
series of the group. Rather than a distinct species,
it is really a ferriferous variety of enstatite, which
owing to partial alteration has acquired a bronze-like
sub-metallic luster on the cleavage surfaces.
Bronzite is sometimes cut and polished, usually in
convex forms, for small ornamental objects, but its
use for this purpose is less extensive than that of
hypersthene. It often has a more-or-less distinct fibrous
structure, and when this is pronounced the sheen has
a certain resemblance to that of cats-eye. Masses sufficiently
large for cutting are found in the norite of the Kupferbergin
the Fichtelgebirge, and in the serpentine of Kraubat
near Leoben in Styria. In this connection mention may
be made of an altered form of enstatite or bronzite
known as bastite or schiller spar. Here, in addition
to schillerization, the original enstatite has been
altered by hydration and the product has the approximate
composition of serpentine. In color bastite is brown
or green with the same metallic sheen as bronzite. The
typical locality is Baste in the Radauthal, Harz, where
patches of pale greyish-green bastite are embedded in
a darker-colored serpentine.
This rock when cut and polished makes an effective
decorative stone, although little used for that purpose.
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