Caoxite is a rare calcium oxalate mineral typically found in association with organic-rich coal environments. It usually occurs as small, delicate yellowish crystals that are highly prized by collectors of rare minerals.
Is this caoxite?
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 caoxite with a known reference. Caoxite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Caoxite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Caoxite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals.
Often confused with
Caoxite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside caoxite
Minerals reported to co-occur with caoxite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca(C₂O₄)·3H₂O
- Mohs hardness
- 2
- Density
- 2.44 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Coal Seams
- Typical price
- $50-300 per specimen
Where rockhounds find caoxite
Classic worldwide localities
- Cegelska, Slovakia
- Most, Czech Republic
Field-hunting tip
Look in coal seams country, the host setting where caoxite typically forms. If you start seeing whewellite, weddellite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find caoxite on the map
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