Medenbachite is a rare secondary mineral found in the oxidation zones of arsenic-rich hydrothermal ore deposits. It typically forms small, distinct tabular crystals with a characteristic orange to reddish-orange color and adamantine luster.

Hardness

4.5

Mohs

Luster

Vitreous to adamantine

Streak

Light yellow

Transparency

Transparent to translucent

mineralrare

Medenbachite

Hardness: 4.5
Luster: Vitreous to adamantine
Streak: Light yellow
Transparency: Transparent to translucent

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Is this medenbachite?

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 medenbachite with a known reference. Medenbachite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: light yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to adamantine.
4
Match the color range
Compare against the expected color range: yellow, brownish yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: crystalline, tabular.

Often confused with

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

mineral

Mixite

Mohs 3-4

How to tell apart: Streak differs, so Medenbachite leaves light yellow, Mixite leaves pale bluish green.

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Often found alongside medenbachite

Minerals reported to co-occur with medenbachite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Bi₂Fe(Cu,Fe)(OH)₂(AsO₄)₂
Mohs hardness: 4.5
Density: 5.9 g/cm³
Colors: Yellow Brownish yellow
Streak: Light yellow
Luster: Vitreous to adamantine
Transparency: Transparent to translucent
Crystal system: Triclinic
Crystal habit: Crystalline, tabular
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: A very rare secondary mineral in a weathered polymetallic sulfide vein

Where rockhounds find medenbachite

Classic worldwide localities

In a quarry near the Borstein cliff, about 1 km east of the town of Reichenbach, Odenwald, Hesse, Germany (type locality)

Field-hunting tip

Where it forms: A very rare secondary mineral in a weathered polymetallic sulfide vein. If you start seeing mixite, preisingerite, alunite in float, you are in the right ground. Typical habit: crystalline, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify medenbachite?+

Mohs hardness is 4.5. Luster: vitreous to adamantine. The streak is light yellow. Common colors include yellow, brownish yellow.

Where is medenbachite found?+

Notable localities include In a quarry near the Borstein cliff, about 1 km east of the town of Reichenbach, Odenwald, Hesse, Germany (type locality).

Is medenbachite safe to handle?+

Medenbachite contains arsenic and copper and calls for real care. Contains arsenic and bismuth; handle with care and wash hands thoroughly after contact.

What rocks look like medenbachite?+

Medenbachite is most often confused with Mixite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with medenbachite?+

Medenbachite commonly co-occurs with Mixite, Preisingerite, Alunite, Goethite, Reichenbachite, Malachite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does medenbachite form in?+

Where it forms: A very rare secondary mineral in a weathered polymetallic sulfide vein. Working float back to the host body is the standard way to chase a fresh occurrence.

What is medenbachite used for?+

Medenbachite is used in collector.

Find medenbachite on the map

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