Columbite-Tantalite is a solid solution series often referred to as coltan, valued primarily as the main ore for tantalum and niobium. Collectors typically look for its characteristic submetallic luster and dense, blocky, or tabular crystals found within complex granitic pegmatites.
Is this columbite-tantalite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch columbite-tantalite with a known reference. Columbite-Tantalite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: black, brownish-black, brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, tabular crystals, massive.
Often confused with
Columbite-Tantalite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Columbite-Tantalite is noticeably harder (Mohs 6 vs. 4.5); streak differs, so Columbite-Tantalite leaves black, Wolframite leaves reddish brown.
How to tell apart: Streak differs, so Columbite-Tantalite leaves black, Cassiterite leaves white, pale brown, pale gray; luster reads submetallic on Columbite-Tantalite and adamantine to adamantine metallic, splendent; may be greasy on fractures on Cassiterite.
How to tell apart: Luster reads submetallic on Columbite-Tantalite and metallic to submetallic on Ilmenite.
Often found alongside columbite-tantalite
Minerals reported to co-occur with columbite-tantalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Fe,Mn)(Nb,Ta)₂O₆
- Mohs hardness
- 6
- Density
- 5.2-8.0 g/cm³
- Colors
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic crystals, tabular crystals, massive
- Cleavage
- Distinct in one direction
- Rarity
- Uncommon
- Uses
- Collector, Ore of tantalum, Ore of niobium
- Host rock
- granite pegmatites
Where rockhounds find columbite-tantalite
1 mapped spotsClassic worldwide localities
- Democratic Republic of the Congo
- Australia
- Brazil
- Canada
- Nigeria
Field-hunting tip
Where it forms: granite pegmatites. If you start seeing quartz, microcline, albite in float, you are in the right ground. Typical habit: prismatic crystals, tabular crystals, massive. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wisconsin. Start trip planning there.
Common questions
How do you identify columbite-tantalite?+
Where is columbite-tantalite found?+
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What rocks look like columbite-tantalite?+
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Find columbite-tantalite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
