Pseudosinhalite is an extremely rare magnesium aluminum borate mineral typically found in metamorphic boron-rich skarn deposits. It often appears as small, colorless to pale yellow prismatic crystals that can be difficult to distinguish from associated borate species without laboratory analysis.
Is this pseudosinhalite?
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 pseudosinhalite with a known reference. Pseudosinhalite sits at Mohs 6.5, 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: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: pseudomorphous.
Often confused with
Pseudosinhalite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Pseudosinhalite is noticeably harder (Mohs 6.5 vs. 5-5.5); streak differs, so Pseudosinhalite leaves white, Ludwigite leaves black to greenish black; luster reads vitreous on Pseudosinhalite and submetallic on Ludwigite.
How to tell apart: Pseudosinhalite is noticeably harder (Mohs 6.5 vs. 3.5-4); streak differs, so Pseudosinhalite leaves white, Warwickite leaves bluish black; luster reads vitreous on Pseudosinhalite and subvitreous to pearly, submetallic on cleavages, commonly dull if altered on Warwickite.
Often found alongside pseudosinhalite
Minerals reported to co-occur with pseudosinhalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₂Al₃B₂O₉(OH)
- Mohs hardness
- 6.5
- Density
- 3.508 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Pseudomorphous
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare mineral in a contact-metasomatic boron-rich iron deposit, a product of retrograde alteration of sinhalite in magnesium-bearing skarn
Where rockhounds find pseudosinhalite
Classic worldwide localities
- Tayozhnoye iron deposit, 550 km south of Yakutsk, Sakha, Russia
Field-hunting tip
Where it forms: A rare mineral in a contact-metasomatic boron-rich iron deposit, a product of retrograde alteration of sinhalite in magnesium-bearing skarn. If you start seeing forsterite, spinel, ludwigite in float, you are in the right ground. Typical habit: pseudomorphous. Train your eye for that shape before scanning the outcrop.
Common questions
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Find pseudosinhalite on the map
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