Fluor-buergerite is a rare iron-rich member of the tourmaline group found primarily in volcanic rhyolite cavities. It is distinguished from other tourmalines by its specific iron-fluorine chemistry and typically appears as deep brown, prismatic crystals often embedded in volcanic matrix.
Is this fluor-buergerite?
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 fluor-buergerite with a known reference. Fluor-buergerite sits at Mohs 7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brown, dark brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals.
Often confused with
Fluor-buergerite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside fluor-buergerite
Minerals reported to co-occur with fluor-buergerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaFe₃Al₆(Si₆O₁₈)(BO₃)₃O₃F
- Mohs hardness
- 7
- Density
- 3.29 g/cm³
- Colors
- Streak
- Yellowish brown
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- rhyolitic volcanic rocks
Where rockhounds find fluor-buergerite
Classic worldwide localities
- Mexquitic, San Luis Potosí, Mexico
Field-hunting tip
Where it forms: rhyolitic volcanic rocks. If you start seeing sanidine, hematite, cristobalite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluor-buergerite?+
Where is fluor-buergerite found?+
What rocks look like fluor-buergerite?+
What minerals are found with fluor-buergerite?+
What kind of rock does fluor-buergerite form in?+
What is fluor-buergerite used for?+
Find fluor-buergerite on the map
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