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, 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.
