Brenkite is an exceptionally rare calcium fluoride carbonate mineral found in hydrothermal deposits. Collectors typically search for small, clear tabular crystals, often associated with fluorite and calcite in alpine-type veins.
Is this brenkite?
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 brenkite with a known reference. Brenkite sits at Mohs ~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: colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, granular masses.
Often confused with
Brenkite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside brenkite
Minerals reported to co-occur with brenkite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂F₂CO₃
- Mohs hardness
- ~5
- Density
- 3.10 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular crystals, granular masses
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In voids and fissures in a porphryritic selbergite [formerly nosean-phonolite]
Where rockhounds find brenkite
Classic worldwide localities
- Schellkopf, 0.5 km west of Brenk, Eifel district, Germany
Field-hunting tip
Where it forms: In voids and fissures in a porphryritic selbergite [formerly nosean-phonolite]. If you start seeing phillipsite, zeophyllite, gismondine in float, you are in the right ground. Typical habit: tabular crystals, granular masses. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify brenkite?+
Where is brenkite found?+
What rocks look like brenkite?+
What minerals are found with brenkite?+
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What is brenkite used for?+
Find brenkite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
