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. Witzkeite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Witzkeite typically shows a vitreous luster.
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.

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: Evaporite Deposits

Where rockhounds find witzkeite

Classic worldwide localities

southeast slope of Punta de Lobos, Tarapacá region, Chile

Field-hunting tip

Look in evaporite deposits country, the host setting where witzkeite typically forms. If you start seeing halite, gypsum, thenardite in float, you are in the right ground. Field specimens usually show a crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify witzkeite?+

Mohs hardness is 2. It typically shows a vitreous luster. 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 Halite, Gypsum, Thenardite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does witzkeite form in?+

Witzkeite typically forms in evaporite deposits. 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.