Bultfonteinite is a rare calcium silicate mineral primarily known from kimberlite pipes and contact-metamorphosed limestone deposits. It typically presents as attractive, radial, or globular white-to-pink clusters that are highly prized by systematic mineral collectors.
Is this bultfonteinite?
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 bultfonteinite with a known reference. Bultfonteinite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bultfonteinite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Bultfonteinite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pink.
- 5Look at form & habitCrystal system: triclinic. Typical habit: radiating globular clusters, lath-like crystals, fibrous aggregates.
Often confused with
Bultfonteinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Bultfonteinite and vitreous to silky on Pectolite.
How to tell apart: Luster reads vitreous on Bultfonteinite and vitreous to pearly on Apophyllite.
Often found alongside bultfonteinite
Minerals reported to co-occur with bultfonteinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₄Si₂O₇(F,OH)₄·H₂O
- Mohs hardness
- 4.5
- Density
- 2.68 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Radiating Globular Clusters, Lath-like Crystals, Fibrous Aggregates
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Kimberlite Pipes, Contact Metamorphic Zones in Limestone
- Typical price
- $20-150 per specimen depending on crystal size and clarity
Where rockhounds find bultfonteinite
Classic worldwide localities
- Bultfontein Mine, Kimberley, South Africa
- Wessels Mine, Kalahari Manganese Field, South Africa
- Crestmore, California, USA
Field-hunting tip
Look in kimberlite pipes, contact metamorphic zones in limestone country, the host setting where bultfonteinite typically forms. If you start seeing calcite, apophyllite, gyrolite in float, you are in the right ground. Field specimens usually show a radiating globular clusters, lath-like crystals, fibrous aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bultfonteinite?+
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How much is bultfonteinite worth?+
What rocks look like bultfonteinite?+
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Find bultfonteinite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
