Preobrazhenskite is a rare magnesium borate mineral typically found in evaporite deposits. Collectors should look for its distinctive white to yellowish platy or rosette-like aggregates often occurring within borate-rich salt domes.
Is this preobrazhenskite?
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 preobrazhenskite with a known reference. Preobrazhenskite sits at Mohs 4.5-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: colorless, yellow, dark gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy crystals, granular aggregates, rosettes.
Often confused with
Preobrazhenskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads pearly on Preobrazhenskite and vitreous, silky if fibrous on Hydroboracite.
How to tell apart: Luster reads pearly on Preobrazhenskite and vitreous to adamantine on Colemanite.
How to tell apart: Preobrazhenskite is noticeably harder (Mohs 4.5-5 vs. 3); luster reads pearly on Preobrazhenskite and vitreous to pearly on cleavages, dull, greasy on Inderite.
Often found alongside preobrazhenskite
Minerals reported to co-occur with preobrazhenskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃B₁₁O₁₅(OH)₉
- Mohs hardness
- 4.5-5
- Density
- 2.45 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy crystals, granular aggregates, rosettes
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In fine-grained halite–polyhalite rock
Where rockhounds find preobrazhenskite
Classic worldwide localities
- Under the Inder borate deposit, and from the Chalkar salt dome, Ak-saı̆ Valley, Uralsk district, Kazakhstan
Field-hunting tip
Where it forms: In fine-grained halite–polyhalite rock. If you start seeing inyoite, halite, polyhalite in float, you are in the right ground. Typical habit: platy crystals, granular aggregates, rosettes. Train your eye for that shape before scanning the outcrop.
Common questions
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Find preobrazhenskite on the map
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