The Mineral omphacite
Omphacite is a rare member of the pyroxene group. It is intermediary in chemical composition between Augite and Jadeite. It is one of the primary minerals that forms eclogite deposits, which is a dense, course grained rock formed at extremely high pressures. It is occasionally associated with Diamond in Diamond deposits.
Light to dark green
White to light green
5 - 6
Translucent to opaque. Rarely transparent.
3.3 - 3.4
1,2 - prismatic at cleavage angles of 87º and 93º (Characteristic of minerals in the pyroxene group).
First described in Stammbach, Bavaria, Germany. Also found in Found in Val d'Osta (Ivrea), and Bric Vert, Italy; Hof, Bayreuth, Germany; Andersdorf, Koralpe Mountains, Austria; Sogn og Fjordane, Norway; and Oyashirazu beach, Itoigawa, Japan. In the U.S, it is found at Reeds Station in the Tiburon Peninsula, Marin County, California; and in Healdsburg, Sonoma Co., California.
Distingushing Similar Minerals
May be difficult to distinguish from other pyroxene minerals such as Augite, Enstatite, and Hedenbergite.