Fahleite is a very rare zinc iron calcium arsenate mineral that occurs as small, tabular, yellow crystals. It is almost exclusively found in the highly mineralized oxidation zone of the Tsumeb mine in Namibia, often associated with other rare secondary arsenates.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareHopeite Group family

Fahleite

Hardness: 3.5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this fahleite?

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 fahleite with a known reference. Fahleite 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. Fahleite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Fahleite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-green.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, radial aggregates.

Often confused with

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

How to tell apart: Legrandite is the harder of the two (Mohs 4.5 vs. 3.5).

Compare →

Often found alongside fahleite

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

All properties

Chemical formula: Zn₂Fe²⁺Ca₂(AsO₄)₂·4H₂O
Mohs hardness: 3.5
Density: 3.32 g/cm³
Colors: Yellow Yellowish-green
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Tabular Crystals, Radial Aggregates
Cleavage: Perfect On {010}
Rarity: Rare
Uses: Collector
Host rock: Oxidized Hydrothermal Lead-zinc-copper Deposits
Typical price: $50-300 per specimen

Where rockhounds find fahleite

Classic worldwide localities

Tsumeb mine, Namibia

Field-hunting tip

Look in oxidized hydrothermal lead-zinc-copper deposits country — that is the host setting where fahleite typically forms. If you start seeing adamite, smithsonite, mimetite in float, you are in the right ground. Field specimens usually show a tabular crystals, radial aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify fahleite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellowish-green.

Where is fahleite found?+

Notable localities include Tsumeb mine, Namibia.

How much is fahleite 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 fahleite safe to handle?+

It contains toxic constituents. Contains arsenic. Handle with care, avoid creating dust, and wash hands thoroughly after handling; keep stored away from food or living areas. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like fahleite?+

Fahleite is most often confused with Hopeite, Parahopeite, Legrandite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with fahleite?+

Fahleite commonly co-occurs with Adamite, Smithsonite, Mimetite, Tsumcorite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fahleite form in?+

Fahleite typically forms in oxidized hydrothermal lead-zinc-copper deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is fahleite used for?+

Fahleite is used in collector.

Find fahleite on the map

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