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 ~3.5, 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: white.
- 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
- ~3.5
- Density
- 2.878 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular crystals, fibrous, radial aggregates, massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- From drillcore into a contact metasomatized limestone near a quartz diorite intrusion associated with a copper deposit in skarn
Where rockhounds find calciborite
Classic worldwide localities
- Novofrolovskoye copper deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, Russia
Field-hunting tip
Where it forms: From drillcore into a contact metasomatized limestone near a quartz diorite intrusion associated with a copper deposit in skarn. If you start seeing sibirskite, calcite, dolomite in float, you are in the right ground. Typical habit: acicular crystals, fibrous, radial aggregates, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify calciborite?+
Where is calciborite found?+
What rocks look like calciborite?+
What minerals are found with calciborite?+
What kind of rock does calciborite form in?+
What is calciborite used for?+
Find calciborite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
