Kerimasite is a rare member of the garnet group characterized by its high zirconium and iron content. It typically forms sharp dodecahedral crystals in alkaline igneous environments and is primarily sought after by advanced systematic mineral collectors.
Is this kerimasite?
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 kerimasite with a known reference. Kerimasite sits at Mohs ~7, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: dark brown.
- 4Look at form & habitCrystal system: cubic. Typical habit: dodecahedral crystals.
Often confused with
Kerimasite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside kerimasite
Minerals reported to co-occur with kerimasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₃Zr₂(Fe₂Si)O₁₂
- Mohs hardness
- ~7
- Density
- 4.104 g/cm³
- Colors
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Dodecahedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A magmatic phase in calcite carbonatite associated with a nephelinitic volcano (Kerimasi) and surrounding pyroclastic rocks (carbonatite agglomerates and tuffs)
Where rockhounds find kerimasite
Classic worldwide localities
- Kerimasi volcano and the Loluni, Kisete and Loolmurwak explosion craters, Gregory rift, northern Tanzania
Field-hunting tip
Where it forms: A magmatic phase in calcite carbonatite associated with a nephelinitic volcano (Kerimasi) and surrounding pyroclastic rocks (carbonatite agglomerates and tuffs). If you start seeing calcite in float, you are in the right ground. Typical habit: dodecahedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kerimasite?+
Where is kerimasite found?+
What rocks look like kerimasite?+
What minerals are found with kerimasite?+
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Find kerimasite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
