Changoite is a rare secondary sulfate mineral typically found as small, colorless to white tabular crystals or crusts in oxidized ore deposits. It is specifically recognized as the zinc-dominant analogue of bloedite and is primarily valued by mineral collectors for its chemical rarity and type locality origin in Chile.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareBloedite Group family

Changoite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this changoite?

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 changoite with a known reference. Changoite sits at Mohs 2-3, 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: colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: anhedral grains, water soluble.

Often confused with

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

How to tell apart: Luster reads vitreous on Changoite and waxy to vitreous on Leonite.

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Often found alongside changoite

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

All properties

Chemical formula: Na₂Zn(SO₄)₂·4H₂O
Mohs hardness: 2-3
Density: 2.50 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Anhedral grains, water soluble
Cleavage: Poor
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral in the oxidized portion of a Cu–Zn sulfide deposit

Where rockhounds find changoite

Classic worldwide localities

San Francisco mine, two km west of the Sierra Gorda railway station, Sierra Gorda district, southwest of Calama, Antofagasta, Chile

Field-hunting tip

Where it forms: A secondary mineral in the oxidized portion of a Cu–Zn sulfide deposit. If you start seeing thénardite, zincian paratacamite, gypsum in float, you are in the right ground. Typical habit: anhedral grains, water soluble. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify changoite?+

Mohs hardness is 2-3. Luster: vitreous. The streak is white. Common colors include colorless.

Where is changoite found?+

Notable localities include San Francisco mine, two km west of the Sierra Gorda railway station, Sierra Gorda district, southwest of Calama, Antofagasta, Chile.

What rocks look like changoite?+

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

What minerals are found with changoite?+

Changoite commonly co-occurs with Thénardite, Zincian paratacamite, Gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does changoite form in?+

Where it forms: A secondary mineral in the oxidized portion of a Cu–Zn sulfide deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is changoite used for?+

Changoite is used in collector.

Find changoite on the map

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