Cassiterite

Common mineral of the oxides and hydroxides class.

kassiterit cassiterite
Cassiterite from China

Cassiterite shop

Origin of name: from Greek κασσίτερος kassiteros meaning tin

Synonyms and trade names: tinstone, tin spar, needle-tin ore
A massive, opaque and colour banded variety is called wood tin

Can be confused with: due to the extremely high specific gravity cassiterite can only be confused with other very dense minerals like cerussite, scheelite, stibiotantalite and zircon

Localities: historically most significant were the deposits in Cornwall. Today cassiterite is mainly mined in Bolivia, Peru, China, Indonesia and Malaysia. Gem grade material mainly comes from Bolivia and China but facettable Cassiterite has also been found in Namibia, Russia, Myanmar, Sri Lanka and the USA.

kassiterit cassiterite

Cassiterit baguette 3.89cts, China

Handling: very sensitive to acids and heat

Worth knowing: cassiterit always was and still is the most important tin ore. It is the oldest ore used by mankind, mined at least since the beginning of the bronze age about 4500 years ago.

Cassiterite shop

Gemmological Properties of Cassiterite

Formula:
SnO2
Crystal system:
tetragonal
Mohs hardness:
6 - 7
Specific gravity:
6.86 - 7.03
Refractive index:
1.990 - 2.105
Max. Birefringence:
0.103
Dispersion:
0.071
Pleochroism:
variable, from none to strong, yellow-green, brown, red-brown
Luminiscence:
inert to weak
Lustre:
adamantine
Cleavage:
indistinct
Fracture:
small conchoidal to uneven
Colour:
brown, black, red, red-brown, yellow(ish), rarely colourless