Cuatrocapaite-(K) is a rare potassium sodium magnesium oxide, typically colorless. It was approved as a distinct mineral species in 2018. It was first described from Torrecillas mine, Iquique Province, Tarapacá Region, Chile.

Hardness

Mohs

Luster

Vitreous to Pearly

Streak

White

Transparency

Transparent

mineralrareCuatrocapaite family

Cuatrocapaite-(K)

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

No image

Is this cuatrocapaite-(k)?

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 cuatrocapaite-(k) with a known reference. Cuatrocapaite-(K) 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. Cuatrocapaite-(K) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Cuatrocapaite-(K) typically shows a vitreous to pearly luster.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: platy crystals, pseudohexagonal, foliated aggregates.

Often confused with

Cuatrocapaite-(K) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Molybdomenite

Mohs 3.5

How to tell apart: Molybdomenite is the harder of the two (Mohs 3.5 vs. 2); luster reads vitreous to pearly on Cuatrocapaite-(K) and pearly on Molybdomenite.

Compare →

Often found alongside cuatrocapaite-(k)

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

All properties

Chemical formula: K₃(NaMg☐)(As₂O₃)₆Cl₆·16H₂O
Mohs hardness: 2
Density: 2.76 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous to Pearly
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Platy Crystals, Pseudohexagonal, Foliated Aggregates
Cleavage: Perfect On {00*1}
Rarity: Rare
Uses: Collector
Host rock: Evaporitic Deposits

Where rockhounds find cuatrocapaite-(k)

Classic worldwide localities

Torrecillas mine, Tarapacá Region, Chile

Field-hunting tip

Look in evaporitic deposits country, the host setting where cuatrocapaite-(k) typically forms. If you start seeing gypsum, anhydrite, halite in float, you are in the right ground. Field specimens usually show a platy crystals, pseudohexagonal, foliated aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cuatrocapaite-(k)?+

Mohs hardness is 2. It typically shows a vitreous to pearly luster. The streak is white. Common colors include colorless.

Where is cuatrocapaite-(k) found?+

Notable localities include Torrecillas mine, Tarapacá Region, Chile.

Is cuatrocapaite-(k) safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like cuatrocapaite-(k)?+

Cuatrocapaite-(K) is most often confused with Molybdomenite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with cuatrocapaite-(k)?+

Cuatrocapaite-(K) commonly co-occurs with Gypsum, Anhydrite, Halite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cuatrocapaite-(k) form in?+

Cuatrocapaite-(K) typically forms in evaporitic deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is cuatrocapaite-(k) used for?+

Cuatrocapaite-(K) is used in collector.

Find cuatrocapaite-(k) on the map

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