RockHoundR

Zubkovaite is a rare calcium copper arsenate that forms prismatic or sometimes lath-like crystals. It was approved as a distinct mineral species in 2018. It was first described from the Arsenatnaya fumarole, Kamchatka peninsula, Far-Eastern Region, Russia.

Hardness
3.5
Mohs
Luster
Vitreous
Streak
Light blue
Transparency
Transparent

Is this zubkovaite?

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 zubkovaite with a known reference. Zubkovaite 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: light blue.
  • 3
    Read the luster
    Hold the specimen under a strong light. Luster: vitreous.
  • 4
    Match the color range
    Compare against the expected color range: bright sky-blue, turquoise, light bluish green.
  • 5
    Look at form & habit
    Crystal system: monoclinic. Typical habit: prismatic or sometimes lath-like crystals.

Often confused with

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

Apophyllite
mineral
Apophyllite
Mohs 4-5

How to tell apart: Streak differs, so Zubkovaite leaves light blue, Apophyllite leaves white.

Compare →

Often found alongside zubkovaite

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

All properties

Chemical formula
Ca₃Cu₃(AsO₄)₄
Mohs hardness
3.5
Density
4.161 g/cm³
Colors
Bright sky-blueTurquoiseLight bluish green
Streak
Light blue
Luster
Vitreous
Transparency
Transparent
Crystal system
Monoclinic
Crystal habit
Prismatic or sometimes lath-like crystals
Cleavage
One imperfect direction (under the microscope)
Rarity
Rare
Uses
Collector
Host rock
alkaline pegmatites

Where rockhounds find zubkovaite

Classic worldwide localities

  • Khibiny Massif, Kola Peninsula, Russia

Field-hunting tip

Where it forms: alkaline pegmatites. If you start seeing apophyllite, natrolite, aegirine in float, you are in the right ground. Typical habit: prismatic or sometimes lath-like crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify zubkovaite?+
Mohs hardness is 3.5. Luster: vitreous. The streak is light blue. Common colors include bright sky-blue, turquoise, light bluish green.
Where is zubkovaite found?+
Notable localities include Khibiny Massif, Kola Peninsula, Russia.
Is zubkovaite safe to handle?+
Zubkovaite contains arsenic and copper and calls for real care. Contains arsenic, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust.
What rocks look like zubkovaite?+
Zubkovaite is most often confused with Apophyllite. A quick hardness test and a streak check separate the look-alikes faster than color alone.
What minerals are found with zubkovaite?+
Zubkovaite commonly co-occurs with apophyllite, natrolite, aegirine, pectolite. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does zubkovaite form in?+
Where it forms: alkaline pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.
What is zubkovaite used for?+
Zubkovaite is used in collector.

Find zubkovaite on the map

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