Enstatite

Enstatite, one of the "rhombic pyroxenes," silicates of iron and magnesia related to augite (q.v.), but crystallising in the Rhombic (i.e. Prismatic) system. They differ in the percentage of iron they contain, Enstatite having less than five per cent. In thin sections it is colourless and not pleochroic. It gives its name to varieties of diorite and dolerite. It is slightly pearly in lustre, almost infusible, has a hardness of 55, and a specific gravity of 3-1 to 3-3.