Tvrdýite is a rare aluminum phosphate mineral related to variscite, typically found as attractive botryoidal crusts or nodules within phosphate-rich sedimentary sequences. Collectors value it for its vibrant green hues and distinctive waxy luster when found in high-quality cabinet specimens.
Is this tvrdýite?
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 tvrdýite with a known reference. Tvrdýite sits at Mohs 4-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Tvrdýite leaves a light olive-green streak.
- 3Read the lusterHold the specimen under a strong light. Tvrdýite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: botryoidal, crusts, massive.
Often confused with
Tvrdýite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tvrdýite leaves light olive-green, Variscite leaves white; luster reads pearly on Tvrdýite and waxy on Variscite.
How to tell apart: Streak differs, so Tvrdýite leaves light olive-green, Wardite leaves white; luster reads pearly on Tvrdýite and vitreous on Wardite.
Often found alongside tvrdýite
Minerals reported to co-occur with tvrdýite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AlPO₄·2H₂O
- Mohs hardness
- 4-5
- Density
- 2.5-2.6 g/cm³
- Colors
- Streak
- Light Olive-green
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Botryoidal, Crusts, Massive
- Cleavage
- Good On {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate Nodules in Sedimentary Rocks
Where rockhounds find tvrdýite
Classic worldwide localities
- Czech Republic
- Germany
Field-hunting tip
Look in phosphate nodules in sedimentary rocks country, the host setting where tvrdýite typically forms. If you start seeing variscite, crandallite, goyazite in float, you are in the right ground. Field specimens usually show a botryoidal, crusts, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tvrdýite?+
Where is tvrdýite found?+
What rocks look like tvrdýite?+
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Find tvrdýite on the map
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