Cassiterite: a short prismatic crystal ranging in color from nearly brown to nearly black, often twinned in a “tin beak” pattern, with the chemical formula SnO₂ (tin oxide). It is very dense, extremely hard, with imperfect cleavage and conchoidal fracture, ranging from transparent to translucent, and has an adamantine luster. Cassiterite is the primary ore mineral for tin extraction, a metal used in many alloys—especially bronze and brass—in soldering materials, in anti-corrosion coatings (tin plating), and in ceramic pigments.
