Picromerite is a water-soluble sulfate mineral often found as an efflorescence in salt deposits or volcanic fumaroles. It typically occurs as white to colorless crusts or small tabular crystals and is prized by mineral collectors of evaporite species.

Hardness

2.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralcommon

Picromerite

Also: Schönite

Hardness: 2.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this picromerite?

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 picromerite with a known reference. Picromerite 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. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: white, colorless, gray, yellow, reddish.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: massive.

Often confused with

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

How to tell apart: Luster reads vitreous on Picromerite and waxy to vitreous on Leonite.

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Often found alongside picromerite

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

All properties

Chemical formula: K₂Mg(SO₄)₂·6H₂O
Mohs hardness: 2.5
Density: 2.028 g/cm³
Colors: White Colorless Gray Yellow Reddish
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Massive
Cleavage: On {201}, perfect (synthetic)
Rarity: Common
Uses: Collector
Host rock: Principally occurs in oceanic bedded salt deposits; a volcanic sublimate in fumaroles; in a sulfate-rich hydrothermal ore deposit

Where rockhounds find picromerite

Classic worldwide localities

Vesuvius, Campania, Italy
Saxony-Anhalt, from the Leopoldshall-Stassfurt district, and at Aschersleben, Germany
Ellers mine, Neuhof, near Fulda, Hessen, Germany
Adolfsglück mine, Schwarmstedt, Lower Saxony, Germany
Kalusz, Stebnyk, and Golyn, Ukraine
Whitby, Yorkshire, England

Field-hunting tip

Where it forms: Principally occurs in oceanic bedded salt deposits; a volcanic sublimate in fumaroles; in a sulfate-rich hydrothermal ore deposit. If you start seeing halite, anhydrite, kainite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify picromerite?+

Mohs hardness is 2.5. Luster: vitreous. The streak is white. Common colors include white, colorless, gray, yellow.

Where is picromerite found?+

Notable localities include Vesuvius, Campania, Italy; Saxony-Anhalt, from the Leopoldshall-Stassfurt district, and at Aschersleben, Germany; Ellers mine, Neuhof, near Fulda, Hessen, Germany; Adolfsglück mine, Schwarmstedt, Lower Saxony, Germany; Kalusz, Stebnyk, and Golyn, Ukraine.

What rocks look like picromerite?+

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

What minerals are found with picromerite?+

Picromerite commonly co-occurs with Halite, Anhydrite, Kainite, Epsomite, Hohmannite, Metavoltine. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does picromerite form in?+

Where it forms: Principally occurs in oceanic bedded salt deposits; a volcanic sublimate in fumaroles; in a sulfate-rich hydrothermal ore deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is picromerite used for?+

Picromerite is used in collector.

Find picromerite on the map

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