Mineral Guide · Mineral

Cassiterite

Cassiterite is the principal ore of tin and a durable oxide mineral valued by collectors for its high density, lustre and dark brown to black crystals.

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Crystal structure

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Mineral properties

Formula: SnO₂
Class: Oxides
Crystal system: Tetragonal
Typical colours: black, brown, yellow, colourless
Lustre: Adamantine, Greasy, Sub-metallic
Hardness: 6.00-7.00
Specific gravity: 6.98-7.01
Crystal habit: Granular, Prismatic
Origin: high-temperature hydrothermal veins, granite-related pegmatites and resistant alluvial placer deposits

What is Cassiterite?

Cassiterite is the principal ore of tin and a durable oxide mineral valued by collectors for its high density, lustre and dark brown to black crystals.

Mineralogy and structure

The reference formula is SnO₂. Cassiterite belongs to the oxides and has a tetragonal crystal system. Cassiterite belongs to the rutile group and has a tetragonal structure. Its high specific gravity and durability help it survive transport into placer deposits.

Colour and appearance

Typical colours include black, brown, yellow, colourless. Crystal habit, lustre, transparency and matrix association are often as diagnostic as colour.

Formation and localities

Cassiterite forms in or is associated with high-temperature hydrothermal veins, granite-related pegmatites and resistant alluvial placer deposits. Important documented localities include Cornwall in England, Bolivia, Malaysia, Tasmania and many granite-related tin districts.

Collecting and care

Cassiterite is best kept as a labelled collector or reference specimen. Protect fragile crystals from impact and prolonged humidity changes. Lead-, arsenic-, chromium- and cobalt-bearing minerals should not be cut, ground or used in jewellery.

Sources and editorial review

Reviewed by NotOnlyRocks Editorial Team

Last reviewed: 31 August 2026

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