Bicchulite is a rare member of the sodalite group often found in contact-metamorphosed limestone or skarns. It typically occurs as massive white grains and is frequently associated with other calcium-rich silicates like mayenite and hydrogrossular.
Is this bicchulite?
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 bicchulite with a known reference. Bicchulite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: powdery, earthy.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, anhedral grains.
Often confused with
Bicchulite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside bicchulite
Minerals reported to co-occur with bicchulite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Al₂SiO₆(OH)₂
- Mohs hardness
- 2.5
- Density
- 2.75 g/cm³
- Colors
- Streak
- White
- Luster
- Powdery, earthy
- Transparency
- Semitransparent
- Crystal system
- Cubic
- Crystal habit
- Massive, anhedral grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In skarns in limestones, formed through alteration of gehlenite subjected to later retrograde hydration reactions
Where rockhounds find bicchulite
Classic worldwide localities
- Fuka, near Bicchu, Okayama Prefecture, and in the Akagané mine, Iwate Prefecture, Japan
- Carneal, Co. Antrim, Ireland
Field-hunting tip
Where it forms: In skarns in limestones, formed through alteration of gehlenite subjected to later retrograde hydration reactions. If you start seeing vesuvianite, hydrogrossular, gehlenite in float, you are in the right ground. Typical habit: massive, anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bicchulite?+
Where is bicchulite found?+
What rocks look like bicchulite?+
What minerals are found with bicchulite?+
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What is bicchulite used for?+
Find bicchulite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
