Auriacusite is a rare copper iron phosphate mineral typically found as small, platy yellow to brownish-yellow crystals. It is primarily known from specific hydrothermal vein deposits such as the Grube Clara in the Black Forest of Germany.
Is this auriacusite?
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 auriacusite with a known reference. Auriacusite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Auriacusite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Auriacusite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brownish-yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy crystals.
Often confused with
Auriacusite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Auriacusite leaves yellow, Ludjibaite leaves light blue; luster reads resinous on Auriacusite and vitreous on Ludjibaite.
How to tell apart: Streak differs — Auriacusite leaves yellow, Pseudomalachite leaves light green; luster reads resinous on Auriacusite and vitreous on Pseudomalachite.
Often found alongside auriacusite
Minerals reported to co-occur with auriacusite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuFe³⁺(PO₄)O
- Mohs hardness
- 3.5
- Density
- 4.21 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find auriacusite
Classic worldwide localities
- Grube Clara, Germany
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where auriacusite typically forms. If you start seeing barite, goethite, quartz in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify auriacusite?+
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Find auriacusite on the map
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