Sborgite is a rare hydrous sodium borate mineral found in arid evaporite environments. It typically occurs as white crusts or tiny tabular crystals that dehydrate quickly when removed from their native environment, making them difficult to preserve in dry climates.
Is this sborgite?
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 sborgite with a known reference. Sborgite 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. 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: tabular crystals, crusts, or efflorescences.
Often confused with
Sborgite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside sborgite
Minerals reported to co-occur with sborgite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(B₅O₆(OH)₄)·3H₂O
- Mohs hardness
- 2
- Density
- 1.713 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals, crusts, or efflorescences
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- Formed in pipes at a reduction works for borates from hot spring lagoons, between 32°C and 60°C (Larderello, Italy)
Where rockhounds find sborgite
Classic worldwide localities
- Larderello, Val di Cecina, Tuscany, Italy
Field-hunting tip
Where it forms: Formed in pipes at a reduction works for borates from hot spring lagoons, between 32°C and 60°C (Larderello, Italy). If you start seeing borax, thénardite, halite in float, you are in the right ground. Typical habit: tabular crystals, crusts, or efflorescences. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sborgite?+
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What rocks look like sborgite?+
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Find sborgite on the map
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