RocksdayColtan vs Wolframite
How to tell them apart
Columbite-tantalite ore, the source of niobium and tantalum used in electronics.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
An iron manganese tungstate and a major ore of tungsten — black, flat and very heavy.
Photo: Didier Descouens, CC BY-SA 4.0
Quick tests
- Scratch glass: Coltan scratches glass (Mohs 6–6.5); Wolframite can't (Mohs 4–4.5).
- Streak (rub on unglazed porcelain): Coltan leaves a dark brown to black streak; Wolframite leaves reddish brown to black.
Key differences
- Wolframite has one perfect cleavage.
Side by side
| Property | Coltan | Wolframite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 6–6.5 | 4–4.5 |
| Luster | Submetallic | Submetallic |
| Streak | Dark brown to black | Reddish brown to black |
| Colors | Black, Brown | Black, Brown |
| Crystal system | Orthorhombic | Monoclinic |
| Specific gravity | 5.3–8 | 7–7.5 |
| Formula | (Fe,Mn)(Nb,Ta)₂O₆ | (Fe,Mn)WO₄ |
| Found in | DR Congo; Rwanda | Panasqueira, Portugal; Jiangxi, China |
Properties that are the same for both are grayed out.
How to identify coltan
- Black, heavy, submetallic grains or plates.
- Dark brown streak.
- Found in granite pegmatites.
Crystal system: Orthorhombic
Full Coltan guide →How to identify wolframite
- Black bladed crystals with one perfect, shiny cleavage.
- Extremely heavy for its size.
- Often with quartz and cassiterite.
Crystal system: Monoclinic
Full Wolframite guide →More comparisons
Could you tell them apart from a blurry close-up?
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