Kilchoanite is a rare calcium silicate mineral typically found in high-temperature contact metamorphic zones. It usually occurs as fine-grained masses or lamellar intergrowths associated with other skarn minerals like rankinite and larnite. It is primarily a collector's mineral of interest for those specializing in rare silicate species from specific localities like Ardnamurchan.
Is this kilchoanite?
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 kilchoanite with a known reference. Kilchoanite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kilchoanite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Kilchoanite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: lamellar, massive, granular.
Often confused with
Kilchoanite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside kilchoanite
Minerals reported to co-occur with kilchoanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₃Si₂O₇
- Mohs hardness
- 5
- Density
- 2.98 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Lamellar, Massive, Granular
- Cleavage
- Distinct On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Limestone or Skarn Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find kilchoanite
Classic worldwide localities
- Kilchoan, Ardnamurchan, Scotland
- Christmas Mountains, Arizona, USA
- Bellerberg, Germany
Field-hunting tip
Look in metamorphosed limestone or skarn deposits country — that is the host setting where kilchoanite typically forms. If you start seeing rankinite, larnite, calcite in float, you are in the right ground. Field specimens usually show a lamellar, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find kilchoanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
