Strassmannite is a rare aluminum sulfate mineral found primarily in the secondary crusts of burning coal dumps. It typically appears as small, thin tabular crystals that are difficult to distinguish from associated sulfate species without analytical testing.

Hardness

2.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Strassmannite

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

No image

Is this strassmannite?

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 strassmannite with a known reference. Strassmannite 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. Strassmannite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Strassmannite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals.

Often confused with

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

Often found alongside strassmannite

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

All properties

Chemical formula: Al(SO₄)(OH)·5H₂O
Mohs hardness: 2.5
Density: 2.32 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Burning Coal Heaps
Typical price: $50-300 per specimen

Where rockhounds find strassmannite

Classic worldwide localities

Friedrichroda, Thuringia, Germany

Field-hunting tip

Look in burning coal heaps country — that is the host setting where strassmannite typically forms. If you start seeing alunogen, pickeringite 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 strassmannite?+

Mohs hardness is 2.5. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless.

Where is strassmannite found?+

Notable localities include Friedrichroda, Thuringia, Germany.

How much is strassmannite 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 strassmannite?+

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

What minerals are found with strassmannite?+

Strassmannite commonly co-occurs with Alunogen, Pickeringite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does strassmannite form in?+

Strassmannite typically forms in burning coal heaps. Working float back to the host body is the standard way to chase a fresh occurrence.

What is strassmannite used for?+

Strassmannite is used in collector.

Find strassmannite on the map

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