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.

Hardness

3.5

Mohs

Luster

Resinous

Streak

Yellow

Transparency

Translucent

mineralrare

Auriacusite

Hardness: 3.5
Luster: Resinous
Streak: Yellow
Transparency: Translucent

Is this auriacusite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch auriacusite with a known reference. Auriacusite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Auriacusite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Auriacusite typically shows a resinous luster.
4
Match the color range
Compare against the expected color range: yellow, brownish-yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: platy crystals.

Often confused with

Auriacusite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Ludjibaite

Mohs 3.5-4

How to tell apart: Streak differs, so Auriacusite leaves yellow, Ludjibaite leaves light blue; luster reads resinous on Auriacusite and vitreous on Ludjibaite.

How to tell apart: Streak differs, so Auriacusite leaves yellow, Pseudomalachite leaves light green; luster reads resinous on Auriacusite and vitreous on Pseudomalachite.

Compare →

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: Yellow Brownish-yellow
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, 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?+

Mohs hardness is 3.5. It typically shows a resinous luster. The streak is yellow. Common colors include yellow, brownish-yellow.

Where is auriacusite found?+

Notable localities include Grube Clara, Germany.

How much is auriacusite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is auriacusite safe to handle?+

It contains toxic constituents. Contains copper and potentially other heavy metals; handle with care and wash hands after contact to avoid ingestion or skin irritation. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like auriacusite?+

Auriacusite is most often confused with Ludjibaite, Pseudomalachite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with auriacusite?+

Auriacusite commonly co-occurs with Barite, Goethite, Quartz, Hematite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does auriacusite form in?+

Auriacusite typically forms in hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is auriacusite used for?+

Auriacusite is used in collector.

Find auriacusite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.