Weilerite is a rare arsenate member of the beudantite group that typically forms as small, distinctive rhombohedral crystals. It is primarily found in hydrothermal vein systems, most notably in the Black Forest region of Germany. Collectors prize it for its unique chemistry and association with secondary arsenic minerals.
Is this weilerite?
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 weilerite with a known reference. Weilerite sits at Mohs 3.5-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Weilerite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Weilerite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellowish, brownish.
- 5Look at form & habitCrystal system: trigonal. Typical habit: rhombohedral crystals, sometimes pseudo-cubic.
Often confused with
Weilerite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Weilerite leaves white, Beudantite leaves yellow.
How to tell apart: Streak differs — Weilerite leaves white, Corkite leaves yellow.
How to tell apart: Streak differs — Weilerite leaves white, Arsendescloizite leaves yellow; luster reads vitreous on Weilerite and greasy on Arsendescloizite.
Often found alongside weilerite
Minerals reported to co-occur with weilerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BaAs₃(AsO₄)(SO₄)(OH)₆
- Mohs hardness
- 3.5-4
- Density
- 4.2-4.4 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Rhombohedral Crystals, Sometimes Pseudo-cubic
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find weilerite
Classic worldwide localities
- Grube Clara, Germany
- Black Forest, Germany
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where weilerite typically forms. If you start seeing barite, quartz, goethite in float, you are in the right ground. Field specimens usually show a rhombohedral crystals, sometimes pseudo-cubic habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find weilerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
