Tephroite

General Information: Chemical Formula:Mn2SiO4 Composition:(Molecular Weight = 201.96 gm)Manganese 54.41 % MnSilicon 13.91 % SiOxygen 31.69 % O  Empirical Formula: Mn2+2(SiO4) Environment:Contact metamorphism of manganese bearing rocks. Locality:Franklin and Sparta, New Jersey, USA. Name Origin:From the Greek tephros - "ash gray" for its color.Physical Properties: Cleavage:[010] Indistinct Color:gray, olive green, bluish green, red, or reddish brown. Density:4.11 - 4.39, Average = 4.25 Diaphaniety:Transparent to translucent Habits:Massive - Granular - Common texture observed in granite and other igneous rock., Granular - Generally occurs as anhedral to subhedral crystals in matrix., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline). Hardness:6.5 - Pyrite Luminescence:None. Luster:Vitreous - Greasy Streak:grayMore details...