Cardite is a rare zinc arsenate, typically white to pinkish white and pale tan. It is a secondary mineral from a sulfide zone with leached sulfide minerals in a weathered Pb-Zn ore deposit. It is associated with anglesite and pyromorphite. It was first described from the mine dumps of the Block 14 Opencut, Broken Hill, New South Wales, Australia.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrare

Cardite

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

No image

Is this cardite?

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 cardite with a known reference. Cardite 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. Cardite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Cardite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, pinkish white, pale tan.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, massive.

Often confused with

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

Often found alongside cardite

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

All properties

Chemical formula: Zn₅.₅(AsO₄)₂(AsO₃OH)(OH)₃·3H₂O
Mohs hardness: 3
Density: 4.02 g/cm³
Colors: White Pinkish White Pale Tan
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals, Massive
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Sedimentary Environments

Where rockhounds find cardite

Classic worldwide localities

mine dumps of the Block 14 Opencut, New South Wales, Australia

Field-hunting tip

Look in sedimentary environments country, the host setting where cardite typically forms. If you start seeing calcite, aragonite, gypsum in float, you are in the right ground. Field specimens usually show a tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cardite?+

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

Where is cardite found?+

Notable localities include mine dumps of the Block 14 Opencut, New South Wales, Australia.

Is cardite safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like cardite?+

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

What minerals are found with cardite?+

Cardite commonly co-occurs with Calcite, Aragonite, Gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cardite form in?+

Cardite typically forms in sedimentary environments. Working float back to the host body is the standard way to chase a fresh occurrence.

What is cardite used for?+

Cardite is used in collector.

Find cardite on the map

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