Goldschmidtite is a rare potassium niobium oxide, typically dark green. It was approved as a distinct mineral species in 2018. It was first described from Koffiefontein kimberlite pipe, ~ 80 km SSE of Kimberley, Kaapvaal Craton, South Africa.
Is this goldschmidtite?
4-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 goldschmidtite with a known reference. Goldschmidtite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 3Match the color rangeCompare against the expected color range: dark green.
- 4Look at form & habitCrystal system: cubic. Typical habit: anhedral to subhedral grains.
Often confused with
Goldschmidtite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Goldschmidtite is noticeably harder (Mohs 3.5 vs. 1.5-2); luster reads adamantine on Goldschmidtite and metallic, brilliant on Sylvanite.
How to tell apart: Luster reads adamantine on Goldschmidtite and metallic on Calaverite.
Often found alongside goldschmidtite
Minerals reported to co-occur with goldschmidtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KNbO₃
- Mohs hardness
- 3.5
- Density
- 5.32 g/cm³
- Colors
- Luster
- Adamantine
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Anhedral to subhedral grains
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An inclusion in a websteritic diamond (whose surface had green and brown radiation damage) from a kimberlite pipe
Where rockhounds find goldschmidtite
Classic worldwide localities
- Koffiefontein kimberlite pipe, ~ 80 km SSE of Kimberley, Kaapvaal Craton, South Africa
Field-hunting tip
Where it forms: An inclusion in a websteritic diamond (whose surface had green and brown radiation damage) from a kimberlite pipe. If you start seeing cr-rich augite, chromite, mg-silicate in float, you are in the right ground. Typical habit: anhedral to subhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify goldschmidtite?+
Where is goldschmidtite found?+
What rocks look like goldschmidtite?+
What minerals are found with goldschmidtite?+
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Find goldschmidtite on the map
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