Langbeinite is a rare potassium magnesium sulfate mineral found primarily in marine evaporite deposits. It typically forms as tetrahedral crystals or massive granular aggregates and is highly valued as a source of potash for high-quality fertilizers.

Hardness

3.5-4

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineraluncommon

Langbeinite

Hardness: 3.5-4
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this langbeinite?

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 langbeinite with a known reference. Langbeinite sits at Mohs 3.5-4, 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: colorless, violet, greenish, gray, yellowish.
5
Look at form & habit
Crystal system: cubic. Typical habit: tetrahedral crystals, massive, granular.

Often confused with

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

mineral

Halite

Mohs 2-2.5

How to tell apart: Langbeinite is noticeably harder (Mohs 3.5-4 vs. 2-2.5).

How to tell apart: Langbeinite is noticeably harder (Mohs 3.5-4 vs. 2).

Compare →

Often found alongside langbeinite

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

All properties

Chemical formula: K₂Mg₂(SO₄)₃
Mohs hardness: 3.5-4
Density: 2.83 g/cm³
Colors: Colorless Violet Greenish Gray Yellowish
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Cubic
Crystal habit: Tetrahedral crystals, massive, granular
Cleavage: None
Rarity: Uncommon
Uses: Collector, Fertilizer, Industrial
Host rock: A principal ore of potash, mined from marine salt deposits

Where rockhounds find langbeinite

Classic worldwide localities

Carlsbad potash district, Eddy Co, New Mexico, USA
Wilhelmshall, near Halberstadt, Germany
Solvayhall, near Bernberg, Germany
Hattord, Hesse, Germany
Hall and Hallstatt, Austria
Stebnyk, near Drogobych, Ukraine

Field-hunting tip

Where it forms: A principal ore of potash, mined from marine salt deposits. If you start seeing carnallite, halite, sylvite in float, you are in the right ground. Typical habit: tetrahedral crystals, massive, granular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify langbeinite?+

Mohs hardness is 3.5-4. Luster: vitreous. The streak is white. Common colors include colorless, violet, greenish, gray.

Where is langbeinite found?+

Notable localities include Carlsbad potash district, Eddy Co, New Mexico, USA; Wilhelmshall, near Halberstadt, Germany; Solvayhall, near Bernberg, Germany; Hattord, Hesse, Germany; Hall and Hallstatt, Austria.

What rocks look like langbeinite?+

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

What minerals are found with langbeinite?+

Langbeinite commonly co-occurs with Carnallite, Halite, Sylvite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does langbeinite form in?+

Where it forms: A principal ore of potash, mined from marine salt deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is langbeinite used for?+

Langbeinite is used in collector, fertilizer, industrial.

Find langbeinite on the map

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