Cassiterite

Lore & Background

Cassiterite derives its name from the Greek κασσίτερος (kassiteros) for 'tin,' with early references found in Homer's Iliad, such as in the description of the Shield of Achilles. The etymology is debated: Liddell-Scott-Jones suggest an Elamite origin via Babylonian kassi-tira and Sanskrit kastīram, while Roman Ghirshman and J. D. Muhly propose a connection to the Kassites, an ancient people of west and central Iran. Pliny the Elder noted that the Greeks called tin 'cassheros,' and Stephanus of Byzantium mentioned an island named Kassitera in the ocean near India as a source of tin.

Reader's Guide

Cassiterite's significance lies in its role as the dominant source of tin from ancient times to the present. It occurs in alluvial or placer deposits due to its weathering resistance and high specific gravity (about 7.0), which facilitates hydraulic mining concentration. Primary deposits are found in high-temperature quartz veins and pegmatites associated with granitic intrusives, notably in Bolivia and the historic mines of Cornwall and Devon, England. The mineral is also a conflict mineral, as fighting over cassiterite deposits in eastern Democratic Republic of the Congo, particularly in Walikale, has fueled regional conflict. Beyond ore, cassiterite is used as a gemstone and collector specimen, and its crystal twinning—often forming 'elbow twins'—is characteristic. Botryoidal or reniform varieties are called wood tin.

Did You Know?

• Cassiterite is a semiconductor.
• Crystal twinning in cassiterite often forms a near-60-degree 'elbow twin'.
• Botryoidal or reniform cassiterite is called wood tin.
• Fighting over cassiterite deposits in Walikale is a major cause of conflict in eastern Democratic Republic of the Congo.