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 to pearly

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 to pearly
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. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to pearly.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: friable, massive.

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: 2.694 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous to pearly
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Friable, massive
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific research
Host rock: Restricted to evaporite deposits of oceanic origin

Where rockhounds find vanthoffite

Classic worldwide localities

Bertram Siding, Imperial Co., California, USA
Wilhelmshall potash mine, northwest of Halberstadt, Saxony, Germany
Berlepsch mine and at Douglashall, Stassfurt-Westeregeln district, Magdeburg, Saxony-Anhalt, Germany
Hall, Tirol, Austria
Borislav, Ukraine
Bikaner evaporite district, Rajasthan, India

Field-hunting tip

Where it forms: Restricted to evaporite deposits of oceanic origin. If you start seeing löweite, langbeinite, halite in float, you are in the right ground. Typical habit: friable, massive. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify vanthoffite?+

Mohs hardness is 3.5. Luster: vitreous to pearly. The streak is white. Common colors include colorless.

Where is vanthoffite found?+

Notable localities include Bertram Siding, Imperial Co., California, USA; Wilhelmshall potash mine, northwest of Halberstadt, Saxony, Germany; Berlepsch mine and at Douglashall, Stassfurt-Westeregeln district, Magdeburg, Saxony-Anhalt, Germany; Hall, Tirol, Austria; Borislav, Ukraine.

What rocks look like vanthoffite?+

Vanthoffite is most often confused with Thénardite, 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 Löweite, Langbeinite, Halite, Blödite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does vanthoffite form in?+

Where it forms: Restricted to evaporite deposits of oceanic origin. 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.