Arangasite is a rare aluminum phosphate mineral typically found as small crusts or fibrous aggregates. It is most easily identified by its occurrence in specific phosphate-rich geological environments where it often forms alongside other secondary phosphate minerals.
Is this arangasite?
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 arangasite with a known reference. Arangasite sits at Mohs 1-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Arangasite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Arangasite typically shows a dull to silky luster.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, massive, crusts.
Often confused with
Arangasite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Wavellite is the harder of the two (Mohs 3.5-4 vs. 1-2); luster reads dull to silky on Arangasite and vitreous on Wavellite.
How to tell apart: Variscite is the harder of the two (Mohs 3.5-4.5 vs. 1-2); luster reads dull to silky on Arangasite and waxy on Variscite.
Often found alongside arangasite
Minerals reported to co-occur with arangasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂(PO₄)(OH,F)₃·3H₂O
- Mohs hardness
- 1-2
- Density
- 2.01 g/cm³
- Colors
- Streak
- White
- Luster
- Dull to Silky
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Massive, Crusts
- Cleavage
- Imperfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-bearing Sedimentary Deposits
Where rockhounds find arangasite
Classic worldwide localities
- Arangas, Spain
- Pechanga Mine, California, USA
Field-hunting tip
Look in phosphate-bearing sedimentary deposits country, the host setting where arangasite typically forms. If you start seeing variscite, quartz in float, you are in the right ground. Field specimens usually show a fibrous, massive, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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What rocks look like arangasite?+
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Find arangasite on the map
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