What is Cassiterite?
Cassiterite is a tin oxide mineral that is found in vein deposits, granitic rocks, pegmatites, areas of contact metamorphism and the altered zone of ore deposits. It is also found in placer deposits where it is most commonly mined and given the name of "stream tin". It is the most widely mined ore of tin.
Physical Properties of Cassiterite |
| Color |
brown, black, reddish brown, brownish black |
| Streak |
colorless |
| Luster |
adamantine, splendent to submetallic |
| Diaphaneity |
opaque to translucent |
| Cleavage |
imperfect |
| Mohs Hardness |
6 - 7 |
| Specific Gravity |
6.8 - 7.1 |
| Distinguishing Characteristics |
high specific gravity, luster, streak, fibrous appearance |
| Chemical Composition |
tin oxide, SnO2 |
| Crystal System |
tetragonal |
Uses of Cassiterite
Cassiterite is the principle ore of tin. In the past, much of the tin was used to produce "tin cans" (actually steel plated with tin) for food containers. However, this use is being rapidly replaced by containers made of glass, plastic, paper, aluminum and other materials. Small amounts are also used to produce solder and polishing compounds.
| Cassiterite from near Keystone, South Dakota. Specimen is approximately 4 inches (10 centimeters) across. |
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| Cassiterite sand from Plateau State, Nigeria, Africa. Placer-mined tin is often called "stream tin". Silt- to sand-size particles of cassiterite. |
| Particles of cassiterite from a placer deposit near Tinton, South Dakota. Specimens are approximately 1/8 inch to 3/8 inch (.3 centimeter to .95 centimeter) across. |
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