Hypersthene is a common, iron-rich pyroxene. The name hypersthene derives from the Greek words hyper, meaning above, and stenos, meaning strength, as hypersthene is a much harder mineral than hornblende, a mineral it is often confused with. Hypersthene is in a series of minerals sometimes listed as enstatite-hypersthene. Other minerals in this series are enstatite, bronzite and ferrosilite.
Bronzite, the greenish brown variety of hypersthene, which is found mostly in Australia, has a bronze-like luster, and is also a collectors' stone. It is dark in color, slightly brittle, and not usually used in jewelry. Hypersthene can be green, grayish black and brown. The overall deep color of hypersthene is due to its 50% content of iron, with inclusions of hematite and goethite. These sparkling inclusions within the stone make it quite distinguishable, as they give the stone an attractive reddish iridescence. Hypersthene is a translucent to opaque stone, which displays a distinct pleochroism. It has good cleavage, uneven fracture, and a vitreous luster.
The stone rates a 5.5 on the Moh's hardness scale. While it is usually too dark in color to facet, it may be cut en cabochon to better display its beautiful sparkling inclusions. Hypersthene occurs in meteorites and igneous and metamorphic rocks. Hypersthene is not industrially mined. Crystals are found in large masses, or in course lamellar or fibrous aggregates.
Most gem quality hypersthene is found in Germany, India, Norway, Mexico, Russia, Sweden, the United Kingdom, Greenland, and the United States. US locations include the Adirondack mountain region of New York, especially at North Creek, Crestmore, California, Comanche County, Oklahoma, and Los Alamos County, New Mexico. However, the gemstone is not very well known, nor is it found in large quantities. Hypersthene's associated minerals include 
quartz, feldspars, iron, biotite, olivine (gem quality 
peridot) and almandine.
