Vanthoffite is a rare sulfate mineral found primarily in marine evaporite deposits. It typically forms as colorless or white crystalline masses associated with other salts like halite and glauberite.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Vanthoffite

Vanthoffite is a rare sulfate mineral found primarily in marine evaporite deposits. It typically forms as colorless or white crystalline masses associated with other salts like halite and glauberite.

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

Is this vanthoffite?

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 vanthoffite with a known reference. Vanthoffite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Vanthoffite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Vanthoffite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, gray.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, massive, granular.

Often confused with

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

Often found alongside vanthoffite

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

All properties

Chemical formula: Na₆Mg(SO₄)₄
Mohs hardness: 3.5
Density: 2.69 g/cm³
Colors: Colorless White Gray
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Massive, Granular
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Evaporite Deposits
Typical price: $20-150 for small specimens

Where rockhounds find vanthoffite

Classic worldwide localities

Bernburg, Germany
Segeberg, Germany
Searles Lake, California, USA
Kalt, Germany

Field-hunting tip

Look in evaporite deposits country — that is the host setting where vanthoffite typically forms. If you start seeing halite, bloedite, glauberite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify vanthoffite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, gray.

Where is vanthoffite found?+

Notable localities include Bernburg, Germany; Segeberg, Germany; Searles Lake, California, USA; Kalt, Germany.

How much is vanthoffite worth?+

Typical asking prices fall in the range of $20-150 for small specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like vanthoffite?+

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

What minerals are found with vanthoffite?+

Vanthoffite commonly co-occurs with Halite, Bloedite, Glauberite, Anhydrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does vanthoffite form in?+

Vanthoffite typically forms in evaporite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is vanthoffite used for?+

Vanthoffite is used in collector, scientific research.

Find vanthoffite on the map

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