Mineralpedia Details for Cassiterite

Named for the Greek word for “tin,” kassiteros, which is the major component of the mineral. Cassiterite is a common and widespread mineral and is the main ore of tin. It forms in mid- to high-temperature hydrothermal veins through granite, granite pegmatites, and rhyolite, can occasionally be found in contact metamorphic deposits, and can also occur in large alluvial placer deposits. Important Cassiterite localities include in Germany, the Czech Republic, France, Portugal, England, Nigeria, Namibia, Indonesia, Malaysia, Australia, China, Brazil, and Bolivia, among thousands of other localities worldwide. Short to long prismatic crystals that are black, brownish black, reddish brown, red, yellow, gray or white and from in radially fibrous botroidal crusts or granular masses.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/cassiterite.pdf

Formula

SnO₂ 

Crystal System

Tetragonal 

Crystal Habit

Prismatic, Massive, Botryoidal 

Cleavage

Perfect, Indistinct, None 

Luster

Adamantine 

Color

brown, brownish black, colorless, green, gray 

Streak

brownish white 

Class

Tetragonal - Ditetragonal Dipyramidal 

Fracture

Irregular 

Hardness

6-7 

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Grey, adamantine, tetragonal Cassiterite crystals from 1cm.

2cm, brownish-red to grey Cassiterite crystal.

Absolutely superb well formed, dark brown Cassiterite crystals to over 2cm with a beautiful adamantine luster and a few smoky Quartz points to 1cm covering matrix.

Most Cassiterite worldwide shows blocky, equant crystals not needle-like crystals like these. This is a known habit, but is uncommon. These groups are to 2mm.

Glassy, lustrous brown Cassiterite crystal to 9mm perched nicely on matrix.

Black crystals are from 5 to 10mm. 

Dark rootbeer-brown Cassiterite crystals with a good adamantine luster with Quartz set on a piece of matrix that sets well without aid. The largest crystal is 2.5cm and is apparently twinned.

Translucent brown Cassiterite twinned crystals from 1.3 to 2cm. 

Deep brown and lustrous, cyclic twinned Cassiterite crystals, the largest to 8mm.

Pegmatite matrix with other minerals such as orthoclase and an unidentified green mineral with deep reddish brown euhedral crystals of Cassiterite to 4mm.

There are very few if any tin mines in the USA. There are plenty of Cassiterite occurences, but this place actually produced some tin - about 1000 pounds. That's nothing in the tin world, but aside from the scarce deposits in the Black Hills, there is very little else on record in terms of viable tin mining. These deposits occured in an area roughly 450 square miles and first found as placers. The prospectors later discovered stringers in Tertiary rhyolite. 

This specimen is a one of those "nuggets", what was once termed "wood tin".

Open vug filled with milky Quartz crystals and 1-3mm dark brown, lustrous, and well-formed Cassiterite crystals. Very nice specimen from one of the planet's greatest tin mining regions. The Great Wheal Fortune was worked for tin from 1855 to 1890. This specimen was actually collected on the mine dumps in 1997.

Exceptionally well formed glassy brown crystals of Cassiterite to 2mm. 

Nice little eudedral set of twinned crystals to 8mm across. 

Four pieces of brown to red-brown, slightly worn pieces of Cassiterite var. Wood Tin that actually do look similar to small pieces of wood. Pieces <1cm to 1.5cm.

Dark brown cubo-octahedral pair.

There is one tiny 1mm cluster of brown acicular crystals of Cassiterite. Good locality specimen.

Solid black or very dark reddish black Cassiterite chunk with a seem about 1cm wide littered with acicular, long slender, Cassiterite crystals to 6mm.

Black anhedral crystals in muscovite matrix.

An older label only states the occurence of Chlorite for the specimen. However viewing this piece closer you will discover incredible, lustrous, sharp, deep amber-brown crystals of Cassiterite to 3.5mm. The Sam eller label also states that the specimen is from the "Stanniferous Vein Section".

Lustrous prismatic crystals with pyramidal terminations. The crystals are about 6mm and show a yellow color when backlit.

2-3mm cyclic twinned Cassiterite crystals. Most of the specimen is Cassiterite with about 25% Quartz.

At first glance, you might think this as another ugly mineral. But upon further examination under the scope you would see preety good brown, twined crystals of Cassiterite to 5mm! And it is from Cornwall, one of the greatest tin mining districts the worl has ever known.

Most of matrix is granular black Cassiterite with associated purple Fluorite anf dark orange Sphalerite.