Bronzite

Bronzite occurs in ultramafic igneous rocks such as peridotite and orthopyroxenite. Mindat lists more than 280 localities, including Kraubath an der Mur in Austria and occurrences in Brazil; Gemdat describes the classic material as coming from Austria.

Bronzite is recognised by its brown color and bronze-like submetallic luster on cleavage surfaces, sometimes with fibrous inclusions. Its iron-dominant counterpart is ferrosilite, and the obsolete name hypersthene was used for darker material midway between enstatite and ferrosilite; Gemdat gives hypersthene a higher refractive index (1.673 to 1.731) and specific gravity (3.45 to 3.55) than bronzite (about 1.668 and 3.35). Under the 1988 nomenclature only enstatite and ferrosilite are species, so exact naming requires chemical analysis.

Bronzite was known long before enstatite, which was described later; Mindat cites a chemical study of bronzite published by Martin Heinrich Klaproth in 1810. Like hypersthene, the name was dropped as a species name by the 1988 pyroxene nomenclature but Mindat still lists bronzite as a variety of enstatite.