Coparsite is a rare copper-chloride mineral discovered in the volcanic fumaroles of the Tolbachik volcano in Russia. It typically forms small, dark green tabular crystals within salt-rich volcanic crusts and is highly prized by advanced mineral collectors.

Hardness
3
Mohs
Luster
Metallic
Streak
Brown
Transparency
Opaque

Is this coparsite?

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 coparsite with a known reference. Coparsite 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. Coparsite leaves a brown streak.
  • 3
    Read the luster
    Hold the specimen under a strong light. Coparsite typically shows a metallic luster.
  • 4
    Match the color range
    Compare against the expected color range: dark green, greenish black.
  • 5
    Look at form & habit
    Crystal system: orthorhombic. Typical habit: tabular crystals.

Often confused with

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

Often found alongside coparsite

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

All properties

Chemical formula
Cu₄OCl₆(OH)₂
Mohs hardness
3
Density
4.94 g/cm³
Streak
Brown
Luster
Metallic
Transparency
Opaque
Crystal system
Orthorhombic
Crystal habit
Tabular Crystals
Cleavage
Perfect On {100}
Rarity
Rare
Uses
Collector
Host rock
Fumarole Deposits

Where rockhounds find coparsite

Classic worldwide localities

  • Tolbachik volcano, Kamchatka, Russia

Field-hunting tip

Look in fumarole deposits country, the host setting where coparsite typically forms. If you start seeing sylvite, halite, tenorite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify coparsite?+
Mohs hardness is 3. It typically shows a metallic luster. The streak is brown. Common colors include dark green, greenish black.
Where is coparsite found?+
Notable localities include Tolbachik volcano, Kamchatka, Russia.
Is coparsite safe to handle?+
It contains toxic constituents. Contains copper and chlorine. Wash hands thoroughly after handling to prevent ingestion or inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.
What rocks look like coparsite?+
Coparsite is most often confused with Atacamite, Paratacamite. A quick hardness test and a streak check separate the look-alikes faster than color alone.
What minerals are found with coparsite?+
Coparsite commonly co-occurs with Sylvite, Halite, Tenorite, Eriocalcite. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does coparsite form in?+
Coparsite typically forms in fumarole deposits. Working float back to the host body is the standard way to chase a fresh occurrence.
What is coparsite used for?+
Coparsite is used in collector.

Find coparsite on the map

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