Pickeringite is a secondary sulfate mineral typically found as efflorescent, fibrous, or needle-like growths in arid environments or mine tailings. Collectors should look for delicate white to pale pink crusts forming in dry, oxidized zones of sulfide ore bodies.
Is this pickeringite?
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 pickeringite with a known reference. Pickeringite sits at Mohs 1.5-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Pickeringite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Pickeringite typically shows a silky luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, yellowish, pale pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, acicular, efflorescent crusts.
Often confused with
Pickeringite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside pickeringite
Minerals reported to co-occur with pickeringite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgAl₂(SO₄)₄·22H₂O
- Mohs hardness
- 1.5-2
- Density
- 1.7-1.8 g/cm³
- Streak
- White
- Luster
- Silky
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Acicular, Efflorescent Crusts
- Cleavage
- Perfect On {010}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Oxidized Zones of Sulfide Deposits, Coal Mine Dumps
- Typical price
- $10-40 per specimen
Where rockhounds find pickeringite
1 mapped spotsClassic worldwide localities
- Chile
- United States (Arizona, Nevada)
- Germany
- Italy
Field-hunting tip
Look in oxidized zones of sulfide deposits, coal mine dumps country — that is the host setting where pickeringite typically forms. If you start seeing alunogen, copiapite, gypsum in float, you are in the right ground. Field specimens usually show a fibrous, acicular, efflorescent crusts habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Missouri — start trip planning there.
Common questions
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Find pickeringite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
