Jaffeite is a rare calcium silicate hydroxide found in high-temperature metamorphic environments such as the Hatrurim formation. It typically forms colorless to white prismatic crystals or radial aggregates and is prized by micromount collectors for its distinct, albeit rare, crystalline structure.
Is this jaffeite?
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 jaffeite with a known reference. Jaffeite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Jaffeite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Jaffeite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals, radial aggregates.
Often confused with
Jaffeite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside jaffeite
Minerals reported to co-occur with jaffeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₆Si₂O₇(OH)₆
- Mohs hardness
- 3.5
- Density
- 2.81 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic Crystals, Radial Aggregates
- Cleavage
- Perfect On {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Rocks of The Sanidinite Facies, Often in Spurrite-merwinite Assemblages
- Typical price
- $50-300 per specimen
Where rockhounds find jaffeite
Classic worldwide localities
- Hatrurim Basin, Israel
- Fuka mine, Japan
- Kilchoan, Scotland
Field-hunting tip
Look in metamorphic rocks of the sanidinite facies, often in spurrite-merwinite assemblages country — that is the host setting where jaffeite typically forms. If you start seeing rankinite, kilchoanite, calcite in float, you are in the right ground. Field specimens usually show a prismatic crystals, radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find jaffeite on the map
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