Sulfoborite is a rare magnesium borate-sulfate mineral that typically forms in evaporite deposits. Collectors value it for its delicate, acicular or prismatic crystal habits often found within salt dome environments.
Is this sulfoborite?
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 sulfoborite with a known reference. Sulfoborite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Sulfoborite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Sulfoborite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellowish, gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic to acicular crystals, often as radiating clusters or aggregates.
Often confused with
Sulfoborite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside sulfoborite
Minerals reported to co-occur with sulfoborite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃(SO₄)(B(OH)₄)₂·(OH,F)₂
- Mohs hardness
- 3.5
- Density
- 2.47 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic to Acicular Crystals, Often as Radiating Clusters or Aggregates
- Cleavage
- Distinct On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Evaporite Deposits
- Typical price
- $20-150 per specimen depending on crystal quality
Where rockhounds find sulfoborite
Classic worldwide localities
- Stassfurt, Germany
- Inder Deposit, Kazakhstan
- Searles Lake, California, USA
- Calingasta, Argentina
Field-hunting tip
Look in evaporite deposits country, the host setting where sulfoborite typically forms. If you start seeing halite, anhydrite, boracite in float, you are in the right ground. Field specimens usually show a prismatic to acicular crystals, often as radiating clusters or aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sulfoborite?+
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How much is sulfoborite worth?+
What rocks look like sulfoborite?+
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Find sulfoborite on the map
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