Cadwaladerite is a very rare aluminum hydroxychloride mineral found in arid desert evaporite deposits. It is known for its extreme solubility in water, requiring collectors to keep specimens in sealed containers to prevent deliquescence or dissolution in humid air.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Cadwaladerite

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

Is this cadwaladerite?

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 cadwaladerite with a known reference. Cadwaladerite 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. Cadwaladerite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Cadwaladerite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, brown, colorless.
5
Look at form & habit
Crystal system: trigonal. Typical habit: fine-grained aggregates.

Often confused with

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

Often found alongside cadwaladerite

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

All properties

Chemical formula: AlCl(OH)₂·4H₂O
Mohs hardness: 2
Density: 2.44 g/cm³
Colors: Yellow Brown Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Fine-grained Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Nitrate-bearing Saline Deposits
Typical price: $50-200 for rare micromounts

Where rockhounds find cadwaladerite

Classic worldwide localities

Cerro Pintados, Chile
Atacama Desert, Chile

Field-hunting tip

Look in nitrate-bearing saline deposits country — that is the host setting where cadwaladerite typically forms. If you start seeing halite, nitratine, darapskite in float, you are in the right ground. Field specimens usually show a fine-grained aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cadwaladerite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is white. Common colors include yellow, brown, colorless.

Where is cadwaladerite found?+

Notable localities include Cerro Pintados, Chile; Atacama Desert, Chile.

How much is cadwaladerite worth?+

Typical asking prices fall in the range of $50-200 for rare micromounts. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like cadwaladerite?+

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

What minerals are found with cadwaladerite?+

Cadwaladerite commonly co-occurs with halite, nitratine, darapskite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cadwaladerite form in?+

Cadwaladerite typically forms in nitrate-bearing saline deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is cadwaladerite used for?+

Cadwaladerite is used in collector.

Find cadwaladerite on the map

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