Larnite is a rare calcium silicate mineral primarily found in high-temperature contact metamorphic environments, such as limestone altered by magma or coal seam combustion. It typically appears as nondescript, colorless to gray masses and is challenging for amateur collectors to identify without professional lab analysis. It is most famous as a synthetic constituent of Portland cement clinker.
Is this larnite?
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 larnite with a known reference. Larnite 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. Larnite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Larnite 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 fine-grained aggregates.
Often confused with
Larnite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside larnite
Minerals reported to co-occur with larnite. 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
- 3.28 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Granular, Massive, Or Fine-grained Aggregates
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Metamorphosed Limestone in Contact Zones or Combustion Metamorphic Complexes
- Typical price
- $20-100 per specimen
Where rockhounds find larnite
Classic worldwide localities
- Scawt Hill, Northern Ireland
- Bellerberg, Germany
- Hatrurim Basin, Israel
- Crestmore, USA
Field-hunting tip
Look in metamorphosed limestone in contact zones or combustion metamorphic complexes country — that is the host setting where larnite typically forms. If you start seeing gehlenite, spurrite, merwinite in float, you are in the right ground. Field specimens usually show a granular, massive, or fine-grained aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify larnite?+
Where is larnite found?+
How much is larnite worth?+
What rocks look like larnite?+
What minerals are found with larnite?+
What kind of rock does larnite form in?+
What is larnite used for?+
Find larnite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
