The Mineral tephroite
Tephroite is uncommon member of the Olivine group. It is the manganese counterpart of Forsterite, and forms a series with Forsterite. Tephroite gets it name from the Greek word "tephros", meaning ash-colored, referring to its ash-gray color habit.
Gray, grayish-green, olive-green, brown, reddish-brown, pink
Translucent. Rarely transparent.
4.0 - 4.1
Vitreous, greasy, waxy
2,1 ; 3,1- forming a 90º angle
Conchoidal to uneven
Worldwide localities for Tephroite include Broken Hill, New South Wales, Australia; the Wessels Mine, Hotazel, Kalahari manganese fields, South Africa; and Langban, Sweden. In the U.S., the most well-known Tephroite is from Franklin, Ogdensburg, and Sparta, all in Sussex Co., New Jersey. Tephroite is also found in the Jail Hill Quarry, Haddam, Middlesex Co., Connecticut.
Distingushing Similar Minerals
Willemite - Different cleavage, fluoresces bright green.
Rhodonite - Usually pinker in color.