Clairite is a very rare ammonium-bearing sulfate mineral often found in the oxidized zones of coal mine dumps. It typically appears as small, yellowish, pearly tabular crystals and is distinguished from common copiapite by its ammonium content and specific geological setting.

Hardness

2.5

Mohs

Luster

Pearly

Streak

Yellow

Transparency

Translucent

mineralrareCopiapite Group family

Clairite

Hardness: 2.5
Luster: Pearly
Streak: Yellow
Transparency: Translucent

Is this clairite?

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 clairite with a known reference. Clairite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Clairite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Clairite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: yellow, brownish-yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals.

Often confused with

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

Often found alongside clairite

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

All properties

Chemical formula: (NH₄)₂Fe³⁺₄(SO₄)₆(OH)₂·7H₂O
Mohs hardness: 2.5
Density: 2.44 g/cm³
Colors: Yellow Brownish-yellow
Streak: Yellow
Luster: Pearly
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Tabular Crystals
Cleavage: Good
Rarity: Rare
Uses: Collector
Host rock: Oxidized Sulfide Deposits
Typical price: $50-300 per specimen

Where rockhounds find clairite

Classic worldwide localities

Friedrichssegen Mine, Germany
Kladno, Czech Republic

Field-hunting tip

Look in oxidized sulfide deposits country — that is the host setting where clairite typically forms. If you start seeing jarosite, gypsum, melanterite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify clairite?+

Mohs hardness is 2.5. It typically shows a pearly luster. The streak is yellow. Common colors include yellow, brownish-yellow.

Where is clairite found?+

Notable localities include Friedrichssegen Mine, Germany; Kladno, Czech Republic.

How much is clairite 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.

What rocks look like clairite?+

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

What minerals are found with clairite?+

Clairite commonly co-occurs with Jarosite, Gypsum, Melanterite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does clairite form in?+

Clairite typically forms in oxidized sulfide deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is clairite used for?+

Clairite is used in collector.

Find clairite on the map

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