Calciborite is a rare calcium borate mineral typically found in skarn deposits formed by the contact metamorphism of boron-rich sediments. It commonly occurs as acicular or fibrous crystals often arranged in radial sprays or dense, massive aggregates within carbonate host rocks.
Is this calciborite?
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 calciborite with a known reference. Calciborite 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. Calciborite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Calciborite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals, fibrous, radial aggregates, massive.
Often confused with
Calciborite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside calciborite
Minerals reported to co-occur with calciborite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaB₂O₄
- Mohs hardness
- 6.5
- Density
- 2.81 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular Crystals, Fibrous, Radial Aggregates, Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Skarn Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find calciborite
Classic worldwide localities
- Sakha Republic, Russia
- Kola Peninsula, Russia
Field-hunting tip
Look in skarn deposits country, the host setting where calciborite typically forms. If you start seeing szaibelyite, ludwigite, calcite in float, you are in the right ground. Field specimens usually show a acicular crystals, fibrous, radial aggregates, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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How much is calciborite worth?+
What rocks look like calciborite?+
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Find calciborite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
