Sanderite is a rare magnesium sulfate mineral that typically forms as a secondary product in salt mines. Collectors should look for delicate white fibrous or needle-like crusts on other evaporite minerals, though it is often prone to dehydration and requires careful storage.
Is this sanderite?
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 sanderite with a known reference. Sanderite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Sanderite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Sanderite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: fibrous, acicular, or efflorescent crusts.
Often confused with
Sanderite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside sanderite
Minerals reported to co-occur with sanderite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Mg(SO₄)₂·2H₂O
- Mohs hardness
- 2
- Density
- 1.74 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Fibrous, Acicular, Or Efflorescent Crusts
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Evaporite Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find sanderite
Classic worldwide localities
- Sander Mine, Thuringia, Germany
- various salt deposits
Field-hunting tip
Look in evaporite deposits country, the host setting where sanderite typically forms. If you start seeing halite, kieserite, carnallite in float, you are in the right ground. Field specimens usually show a fibrous, acicular, or efflorescent crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find sanderite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
