Weddellite is a rare calcium oxalate mineral typically found in sedimentary environments and sometimes associated with biological processes. It most commonly appears as small, colorless or pale yellow tetragonal bipyramidal crystals that are notable for their unique formation history in organic-rich settings.
Is this weddellite?
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 weddellite with a known reference. Weddellite 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. Weddellite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Weddellite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, pale yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: bipyramidal crystals.
Often confused with
Weddellite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside weddellite
Minerals reported to co-occur with weddellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaC₂O₄·2H₂O
- Mohs hardness
- 3.5
- Density
- 1.92 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Bipyramidal Crystals
- Cleavage
- Distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sedimentary Deposits and Organic Rich Environments
- Typical price
- $20-100 per specimen
Where rockhounds find weddellite
Classic worldwide localities
- Weddell Sea
- various sedimentary deposits
- biological urinary sediments
Field-hunting tip
Look in sedimentary deposits and organic rich environments country — that is the host setting where weddellite typically forms. If you start seeing whewellite, calcite in float, you are in the right ground. Field specimens usually show a bipyramidal crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify weddellite?+
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Find weddellite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
