Rokühnite is a very rare iron chloride hydrate that typically forms as a secondary mineral in oxidized iron-ore deposits. Because it is highly deliquescent and sensitive to humidity, it must be stored in a sealed, dry environment to prevent it from absorbing moisture and dissolving.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Rokühnite

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this rokühnite?

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 rokühnite with a known reference. Rokühnite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Rokühnite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Rokühnite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, pale green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, crusts.

Often confused with

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

How to tell apart: Streak differs — Rokühnite leaves white, Erythrite leaves pale pink; luster reads vitreous on Rokühnite and adamantine to pearly on Erythrite.

Compare →

Often found alongside rokühnite

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

All properties

Chemical formula: FeCl₂·2H₂O
Mohs hardness: 2
Density: 2.33 g/cm³
Colors: Yellow Pale Green
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Crusts
Cleavage: Distinct
Rarity: Rare
Uses: Collector
Host rock: Oxidized Hydrothermal Iron Deposits
Typical price: $50-300 per specimen

Where rockhounds find rokühnite

Classic worldwide localities

Kopparberg, Sweden
Saxony, Germany

Field-hunting tip

Look in oxidized hydrothermal iron deposits country — that is the host setting where rokühnite typically forms. If you start seeing hematite, goethite, lawrencite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify rokühnite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is white. Common colors include yellow, pale green.

Where is rokühnite found?+

Notable localities include Kopparberg, Sweden; Saxony, Germany.

How much is rokühnite 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 rokühnite?+

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

What minerals are found with rokühnite?+

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

What kind of rock does rokühnite form in?+

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

What is rokühnite used for?+

Rokühnite is used in collector.

Find rokühnite on the map

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