Calcio-olivine, more formally known as larnite, is a rare calcium silicate mineral primarily found in high-temperature contact metamorphic zones. It typically occurs in limestone xenoliths within igneous rocks and is often difficult to distinguish from associated calcium silicates without specialized analysis.
Is this calcio-olivine?
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 calcio-olivine with a known reference. Calcio-olivine 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. Calcio-olivine leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Calcio-olivine typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular, massive, or lath-like crystals.
Often confused with
Calcio-olivine vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside calcio-olivine
Minerals reported to co-occur with calcio-olivine. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂SiO₄
- Mohs hardness
- 6
- Density
- 3.31 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Granular, Massive, Or Lath-like Crystals
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Contact Metamorphosed Limestone
- Typical price
- $20-150 per specimen depending on size
Where rockhounds find calcio-olivine
Classic worldwide localities
- Scawt Hill, Northern Ireland
- Kilchoan, Scotland
- Negev Desert, Israel
Field-hunting tip
Look in contact metamorphosed limestone country — that is the host setting where calcio-olivine typically forms. If you start seeing gehlenite, spurrite, perovskite in float, you are in the right ground. Field specimens usually show a granular, massive, or lath-like crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify calcio-olivine?+
Where is calcio-olivine found?+
How much is calcio-olivine worth?+
What rocks look like calcio-olivine?+
What minerals are found with calcio-olivine?+
What kind of rock does calcio-olivine form in?+
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Find calcio-olivine on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
