Adamite is a secondary mineral found in the oxidation zones of zinc-rich mineral deposits. Collectors prize it for its vibrant yellow to green colors and frequently lustrous, radial crystal sprays or botryoidal crusts.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent to translucent

mineraluncommon

Adamite

Hardness: 3.5
Luster: Vitreous
Streak: White
Transparency: Transparent to translucent

Is this adamite?

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 adamite with a known reference. Adamite sits at Mohs 3.5, 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: yellow, green, colorless, white, violet, pink, yellowish green.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: druse, encrustations, tabular.

Often confused with

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

How to tell apart: Hemimorphite is the harder of the two (Mohs 4.5-5 vs. 3.5).

How to tell apart: Conichalcite is the harder of the two (Mohs 4.5 vs. 3.5); streak differs, so Adamite leaves white, Conichalcite leaves green.

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Often found alongside adamite

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

All properties

Chemical formula: Zn₂(AsO₄)(OH)
Mohs hardness: 3.5
Density: 4.32-4.48 g/cm³
Colors: Yellow Green Colorless White Violet Pink Yellowish green
Streak: White
Luster: Vitreous
Transparency: Transparent to translucent
Crystal system: Orthorhombic
Crystal habit: Druse, encrustations, tabular
Cleavage: {101}, good; {010}, poor
Fluorescence: Yellow green under SW and LW UV
Rarity: Uncommon
Uses: Collector
Host rock: A secondary mineral in the oxidized zone of zinc- and arsenic-bearing hydrothermal mineral deposits

Where rockhounds find adamite

Classic worldwide localities

Gold Hill, Tooele Co., Utah, and in the Mohawk mine, Clark Mountains, San Bernardino Co., California, USA
Chañarcillo, south of Copiapó, Atacama, Chile
Ojuela mine, Mapimí, Durango, Mexico
Hidalgo mine, Zimapán, Hidalgo, Mexico
Santa Eulalia, Chihuahua, Mexico
Cap Garonne mine, near le Pradet, Var, France

Field-hunting tip

Where it forms: A secondary mineral in the oxidized zone of zinc- and arsenic-bearing hydrothermal mineral deposits. If you start seeing smithsonite, hemimorphite, scorodite in float, you are in the right ground. Typical habit: druse, encrustations, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify adamite?+

Mohs hardness is 3.5. Luster: vitreous. The streak is white. Common colors include yellow, green, colorless, white.

Where is adamite found?+

Notable localities include Gold Hill, Tooele Co., Utah, and in the Mohawk mine, Clark Mountains, San Bernardino Co., California, USA; Chañarcillo, south of Copiapó, Atacama, Chile; Ojuela mine, Mapimí, Durango, Mexico; Hidalgo mine, Zimapán, Hidalgo, Mexico; Santa Eulalia, Chihuahua, Mexico.

Is adamite safe to handle?+

Adamite contains arsenic and calls for real care. Contains arsenic, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid grinding or creating mineral dust.

What rocks look like adamite?+

Adamite is most often confused with Smithsonite, Hemimorphite, Conichalcite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with adamite?+

Adamite commonly co-occurs with Smithsonite, Hemimorphite, Scorodite, Olivenite, Calcite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does adamite form in?+

Where it forms: A secondary mineral in the oxidized zone of zinc- and arsenic-bearing hydrothermal mineral deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is adamite used for?+

Adamite is used in collector.

Find adamite on the map

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