Cassiterite

Some varieties of cassiterite are also known as “wood tin.”

Mineral formula: SnO₂

Mineral group: member of the Rutile group

Crystal system: tetragonal

Crystal habit: Fibrous, botryoidal crusts or concretionary masses. Granular, coarse to fine.

Cleavage: {100} imperfect, {110} indistinct.

Fracture: irregular / uneven, sub-conchoidal

Color: black, yellow, brown, red or white

Luster: adamantine, greasy, sub-metallic

Diaphaneity: transparent, translucent or opaque

Moh’s scale hardness: 6 - 7

Streak: brownish white, white, or grayish

Specific gravity: 6.98 – 7.01

Named after: the term “Cassiterides” referring to 'islands off the western coast of Europe' in pre-Roman times (the exact location of these 'islands' has been hotly debated over the years, current thought is that the source was probably mainland Spain and that even 2000 years ago, traders had a habit of providing misleading locality information to protect their sources).

Geological occurrence: The primary ore of Tin, this mineral is found in hydrothermal veins and pegmatites associated with granite intrusions. Because of its durability, it is also frequently found concentrated in alluvial placer deposits, sometimes in large enough quantities to be commercially exploitable, as in Malaysia, for example.