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.
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.
