Quick Facts
Formation & Origin
Cassiterite is tin oxide - the primary and almost sole ore of tin, one of the first metals smelted by humans. Tin's role in creating bronze (an alloy of copper and tin) makes cassiterite one of the most historically important minerals in human civilization. The Bronze Age (roughly 3300-1200 BCE) was only possible because ancient peoples figured out how to smelt cassiterite.
Cornwall, England, was one of the ancient world's major tin sources. Phoenician traders sailed from the Mediterranean to Cornwall for tin, creating one of the longest trade routes of the ancient world. The 'Cassiterides' (Tin Islands) were mentioned by Greek historians as a mysterious source of tin at the edge of the known world - almost certainly referring to Cornwall or the Isles of Scilly.
Cassiterite forms in high-temperature hydrothermal veins and pegmatites associated with granitic magma. Its extreme density (6.99) causes it to concentrate in alluvial placer deposits, which were the easiest ancient source to exploit.
Identification Guide
Cassiterite is identified by its dark brown to black color, extreme density (6.99 - very heavy), adamantine luster (almost diamond-like shine), and tetragonal crystal habit. The combination of dark color with brilliant adamantine luster is striking.
Distinguish from magnetite (magnetic, slightly less dense), hematite (red-brown streak vs white), and black tourmaline (different luster, striated). Cassiterite's adamantine luster on dark surfaces and extreme heft are its best diagnostic features.
Spotting Fakes
Cassiterite is a specialist collector mineral not commonly faked. The extreme density is the simplest verification - cassiterite feels noticeably heavier than similarly sized dark minerals. Well-crystallized specimens from Bolivia or historical Cornish pieces command premiums based on provenance.
Cultural & Metaphysical Traditions
Presented as cultural traditions, not scientific evidence
Cassiterite's metaphysical profile is defined by its Bronze Age significance. Practitioners who work with it associate it with innovation, problem-solving, and creating something new from combining different elements (as bronze combines copper and tin). Its connection to some of humanity's earliest metallurgy gives it associations with ancestral knowledge and the roots of civilization.
Where It's Found
Exceptional crystal specimens
Major world producer
Historic alluvial tin source
Historic tin mining for 4,000 years
Price Guide
Good to Know
Scratch test: At hardness 6.5, Cassiterite resists scratching from a knife but can be scratched by quartz. Best for pendants and earrings rather than rings.
Sources: Found in 4 notable locations worldwide, from Bolivia to Cornwall.
Heft test: With a specific gravity of 6.99, Cassiterite feels surprisingly heavy for its size. This weight is actually a useful identification tool.