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 — that is 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?+
Where is sulfoborite found?+
How much is sulfoborite worth?+
What rocks look like sulfoborite?+
What minerals are found with sulfoborite?+
What kind of rock does sulfoborite form in?+
What is sulfoborite used for?+
Find sulfoborite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
