.77" Gemmy Cassiterite Crystal - Rwanda

Cassiterite, also known as tinstone, is the primary ore of tin. When pure, cassiterite will be colorless, but in most cases impurities will result in brown or black crystals. It is typically found in hydrothermal veins and pegmatites in regions of granite intrusion. In the appropriate environment, it can also precipitate from volcanic gas.

Chemical Formula: SnO2 (tin oxide)