Fencooperite, gillespite, sanbornite

Black grains of fencooperite in association with red grains of gillespite in white sanbornite. Transparent, glassy grains form celsian. Fencooperite and gillespite are extremely rare silicates of barium and iron; fencooperite is found only at two locations in the world. Sanbornite is a very rare barium silicate. The sample of these rare minerals comes from the Trumbull Peak deposit in the USA, which is also the type locality for fencooperite and sanbornite. The samples were personally collected in 1973 by J. F. Cooper, after whom fencooperite is named.