RocksdayCassiterite vs Coltan
How to tell them apart
Tin dioxide, the main ore of tin — heavy, shiny brown-black crystals.
Photo: CarlesMillan, CC BY-SA 3.0
Columbite-tantalite ore, the source of niobium and tantalum used in electronics.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Streak (rub on unglazed porcelain): Cassiterite leaves a white to pale brown streak; Coltan leaves dark brown to black.
Key differences
- Cassiterite has a pale streak.
Side by side
| Property | Cassiterite | Coltan |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 6–7 | 6–6.5 |
| Luster | Adamantine to submetallic | Submetallic |
| Streak | White to pale brown | Dark brown to black |
| Colors | Brown, Black, Yellow | Black, Brown |
| Crystal system | Tetragonal | Orthorhombic |
| Specific gravity | 6.8–7.1 | 5.3–8 |
| Formula | SnO₂ | (Fe,Mn)(Nb,Ta)₂O₆ |
| Found in | Cornwall, England; Llallagua, Bolivia | DR Congo; Rwanda |
Properties that are the same for both are grayed out.
How to identify cassiterite
- Very heavy for a non-metallic mineral.
- Brown to black with a brilliant luster.
- Light-colored streak despite the dark color.
Crystal system: Tetragonal
Full Cassiterite guide →How to identify coltan
- Black, heavy, submetallic grains or plates.
- Dark brown streak.
- Found in granite pegmatites.
Crystal system: Orthorhombic
Full Coltan guide →More comparisons
Could you tell them apart from a blurry close-up?
Play today's Rocksday