Agardite-(Ce) is a rare secondary mineral typically found as delicate, needle-like crystals or radiating tufts in the oxidation zones of copper deposits. It is best identified by its vibrant yellowish-green color and habit, though it is often visually indistinguishable from other members of the mixite group without chemical analysis.

Hardness

Mohs

Luster

Vitreous to silky

Streak

Greenish to pale yellow

Transparency

Transparent

mineralrareMixite Group family

Agardite-(Ce)

Hardness: ~3
Luster: Vitreous to silky
Streak: Greenish to pale yellow
Transparency: Transparent

Is this agardite-(ce)?

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 agardite-(ce) with a known reference. Agardite-(Ce) 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: greenish to pale yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to silky.
4
Match the color range
Compare against the expected color range: yellow green.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: acicular.

Often confused with

Agardite-(Ce) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Mixite

Mohs 3-4

How to tell apart: Streak differs, so Agardite-(Ce) leaves greenish to pale yellow, Mixite leaves pale bluish green.

Often found alongside agardite-(ce)

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

All properties

Chemical formula: Cu₆Ce(AsO₄)₃(OH)₆·3H₂O
Mohs hardness: ~3
Density: 3.70 g/cm³
Colors: Yellow green
Streak: Greenish to pale yellow
Luster: Vitreous to silky
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Acicular
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In the oxidation zone of polymetallic sulfide deposits

Where rockhounds find agardite-(ce)

Classic worldwide localities

Clara mine, near Oberwolfach, central Black Forest, Germany

Field-hunting tip

Where it forms: In the oxidation zone of polymetallic sulfide deposits. If you start seeing barite, quartz, goethite in float, you are in the right ground. Typical habit: acicular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify agardite-(ce)?+

Mohs hardness is ~3. Luster: vitreous to silky. The streak is greenish to pale yellow. Common colors include yellow green.

Where is agardite-(ce) found?+

Notable localities include Clara mine, near Oberwolfach, central Black Forest, Germany.

Is agardite-(ce) safe to handle?+

Agardite-(Ce) contains arsenic and copper and calls for real care. Contains copper and arsenic. Wash hands thoroughly after handling and avoid inhaling dust when cleaning specimens.

What rocks look like agardite-(ce)?+

Agardite-(Ce) is most often confused with Mixite, Agardite-(Y). A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with agardite-(ce)?+

Agardite-(Ce) commonly co-occurs with Barite, Quartz, Goethite, Cornwallite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does agardite-(ce) form in?+

Where it forms: In the oxidation zone of polymetallic sulfide deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is agardite-(ce) used for?+

Agardite-(Ce) is used in collector.

Find agardite-(ce) on the map

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