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 to translucent

mineralrare

Leightonite

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

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. 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: blue green, light blue.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic.

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: 2.95 g/cm³
Colors: Blue green Light blue
Streak: White
Luster: Vitreous
Transparency: Transparent to translucent
Crystal system: Orthorhombic
Crystal habit: Prismatic
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific research
Host rock: Of localized occurrence in the oxidized zone of a copper deposit, probably formed under conditions of low acidity (Chuquicamata, Chile)

Where rockhounds find leightonite

Classic worldwide localities

Chuquicamata, Antofagasta, Chile
Tsumeb, Namibia

Field-hunting tip

Where it forms: Of localized occurrence in the oxidized zone of a copper deposit, probably formed under conditions of low acidity (Chuquicamata, Chile). If you start seeing natrochalcite, blödite, atacamite in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify leightonite?+

Mohs hardness is 3. Luster: vitreous. The streak is white. Common colors include blue green, light blue.

Where is leightonite found?+

Notable localities include Chuquicamata, Antofagasta, Chile; Tsumeb, Namibia.

Is leightonite safe to handle?+

Leightonite contains copper. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

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 Natrochalcite, Blödite, Atacamite, Bellingerite, Kröhnkite, Gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does leightonite form in?+

Where it forms: Of localized occurrence in the oxidized zone of a copper deposit, probably formed under conditions of low acidity (Chuquicamata, Chile). 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.