cassiteritetype

Cassiterite is a tin oxide mineral with the chemical composition SnO2. It is the primary source of tin and is a common mineral found in granitic pegmatites, alluvial deposits, and hydrothermal veins. Cassiterite is a dense, black or metallic-gray mineral with a metallic luster, often exhibiting a distinct octahedral or trigonal-hexagonal crystal habit.

Cassiterite is typically found in rocks associated with granitic plutons, where it is commonly associated with other tin-bearing minerals such as stannite and sulfides. It can also be found in hydrothermal veins, where it is often accompanied by other minerals such as quartz and sulfides. The mineral has been an important source of tin for thousands of years, with evidence of cassiterite mining dating back to ancient civilizations in China, Europe, and Southeast Asia.

The chemistry of cassiterite involves the tin ion (Sn4+) in a tetrahedral coordination with four oxygen atoms. The crystal structure of cassiterite is one of the most stable known for a tin oxide, which is due in part to the diamagnetic nature of the tin ion and its relatively low charge. The hardness and density of cassiterite are both relatively high for a tin oxide mineral, with a Mohs hardness of 6.8 and a density of approximately 7.0 g/cm3. The high density and hardness make cassiterite an important ore for the extraction of tin, which is used in a wide variety of industrial applications.