Chaidamuite is a rare secondary sulfate mineral typically found as small, yellow, translucent crystals in the oxidation zones of ore deposits. It is named after its type locality in the Qaidam Basin of China and is highly sought after by collectors of rare sulfate species.

Hardness

2.5-3

Mohs

Luster

Vitreous

Streak

Pale yellow

Transparency

Translucent

mineralrare

Chaidamuite

Hardness: 2.5-3
Luster: Vitreous
Streak: Pale yellow
Transparency: Translucent

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Is this chaidamuite?

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 chaidamuite with a known reference. Chaidamuite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: brown, yellowish brown.
5
Look at form & habit
Crystal system: triclinic. Typical habit: prismatic, tabular.

Often confused with

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

mineral

Copiapite

Mohs 2.5-3

How to tell apart: Luster reads vitreous on Chaidamuite and pearly on {010} on Copiapite.

How to tell apart: Streak differs, so Chaidamuite leaves pale yellow, Coquimbite leaves white.

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Often found alongside chaidamuite

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

All properties

Chemical formula: ZnFe³⁺(SO₄)₂(OH)·4H₂O
Mohs hardness: 2.5-3
Density: 2.722 g/cm³
Colors: Brown Yellowish brown
Streak: Pale yellow
Luster: Vitreous
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Prismatic, tabular
Cleavage: On {001} and {100}, perfect
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral in the oxidized portions of a Pb–Zn–Fe sulfide deposit

Where rockhounds find chaidamuite

Classic worldwide localities

Xitieshan Pb–Zn mine, south of Mt. Qilianshan, Chaidamu, Qinghai Province, China

Field-hunting tip

Where it forms: A secondary mineral in the oxidized portions of a Pb–Zn–Fe sulfide deposit. If you start seeing coquimbite, copiapite, butlerite in float, you are in the right ground. Typical habit: prismatic, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify chaidamuite?+

Mohs hardness is 2.5-3. Luster: vitreous. The streak is pale yellow. Common colors include brown, yellowish brown.

Where is chaidamuite found?+

Notable localities include Xitieshan Pb–Zn mine, south of Mt. Qilianshan, Chaidamu, Qinghai Province, China.

What rocks look like chaidamuite?+

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

What minerals are found with chaidamuite?+

Chaidamuite commonly co-occurs with Coquimbite, Copiapite, Butlerite, Zincobotryogen. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does chaidamuite form in?+

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

What is chaidamuite used for?+

Chaidamuite is used in collector.

Find chaidamuite on the map

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