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 — that is 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
How do you identify calciborite?+
Where is calciborite found?+
How much is calciborite worth?+
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.
