Witzkeite is a rare sodium potassium calcium sulfate that forms colorless crystals. It occurs in the oxidation zone of a guano deposit in an arid climate. It is associated with dittmanite and nitratine. It was first described from the southeast slope of Punta de Lobos, Tarapacá region, ~ 90 km south of Iquique, Chile.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Witzkeite

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this witzkeite?

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 witzkeite with a known reference. Witzkeite sits at Mohs 2, 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.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: crystals.

Often confused with

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

Often found alongside witzkeite

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

Nitratine
mineral · Mohs 1.5-2

All properties

Chemical formula: Na₄K₄Ca(NO₃)₂(SO₄)₄·2H₂O
Mohs hardness: 2
Density: 2.40 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Crystals
Cleavage: {001}, distinct
Rarity: Rare
Uses: Collector
Host rock: In the oxidation zone of a guano deposit in an arid climate

Where rockhounds find witzkeite

Classic worldwide localities

Southeast slope of Punta de Lobos, Tarapacá region, Chile

Field-hunting tip

Where it forms: In the oxidation zone of a guano deposit in an arid climate. If you start seeing dittmanite, nitratine in float, you are in the right ground. Typical habit: crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify witzkeite?+

Mohs hardness is 2. Luster: vitreous. The streak is white. Common colors include colorless.

Where is witzkeite found?+

Notable localities include Southeast slope of Punta de Lobos, Tarapacá region, Chile.

What rocks look like witzkeite?+

Witzkeite 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 witzkeite?+

Witzkeite commonly co-occurs with Dittmanite, Nitratine. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does witzkeite form in?+

Where it forms: In the oxidation zone of a guano deposit in an arid climate. Working float back to the host body is the standard way to chase a fresh occurrence.

What is witzkeite used for?+

Witzkeite is used in collector.

Find witzkeite on the map

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