Leightonite is a rare copper sulfate mineral primarily found in the oxidized zones of arid copper mines in Chile. It typically forms pale yellow to colorless tabular crystals or crusts and is highly valued by specialized mineral collectors due to its restricted distribution.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Leightonite

Hardness: 3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this leightonite?

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 leightonite with a known reference. Leightonite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Leightonite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Leightonite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: pale yellow, white, colorless.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, crusts, granular aggregates.

Often confused with

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

Often found alongside leightonite

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

All properties

Chemical formula: K₂Ca₂Cu(SO₄)₄·2H₂O
Mohs hardness: 3
Density: 2.98 g/cm³
Colors: Pale Yellow White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular Crystals, Crusts, Granular Aggregates
Cleavage: Perfect On {001}
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Oxidized Copper Deposits
Typical price: $50-300 per specimen

Where rockhounds find leightonite

Classic worldwide localities

Chuquicamata Mine, Chile
Potrerillos, Chile

Field-hunting tip

Look in oxidized copper deposits country — that is the host setting where leightonite typically forms. If you start seeing chalcanthite, kröhnkite, gypsum in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, granular aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify leightonite?+

Mohs hardness is 3. It typically shows a vitreous luster. The streak is white. Common colors include pale yellow, white, colorless.

Where is leightonite found?+

Notable localities include Chuquicamata Mine, Chile; Potrerillos, Chile.

How much is leightonite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like leightonite?+

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

What minerals are found with leightonite?+

Leightonite commonly co-occurs with Chalcanthite, Kröhnkite, Gypsum, Atacamite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does leightonite form in?+

Leightonite typically forms in oxidized copper deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is leightonite used for?+

Leightonite is used in collector, scientific research.

Find leightonite on the map

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