The terms “Fencooperit”, “gillespit”, and “sanbornit” do not appear to have translations in the vector store, and they are likely to be scientific names or proper nouns. Therefore, they should be kept in their original Czech form: – Fencooperit – Gillespit – Sanbornit

Black grains of fencooperite in association with red grains of gillespite in white sanbornite. Clear, vitreous grains are formed by celsian. Fencooperite and gillespite are extremely rare silicates of barium and iron; fencooperite occurs only at two localities in the world. Sanbornite is a very rare barium silicate. This 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 specimens were collected personally by J. F. Cooper in 1973, after whom fencooperite is named.