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

mineralrare

Zubkovaite

Hardness: 3.5
Luster: Vitreous
Streak: Light Blue
Transparency: Transparent

No image

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. Zubkovaite leaves a light blue streak.
3
Read the luster
Hold the specimen under a strong light. Zubkovaite typically shows a vitreous luster.
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.

mineral

Apophyllite

Mohs 4.5-5

How to tell apart: Apophyllite is the harder of the two (Mohs 4.5-5 vs. 3.5); streak differs, so Zubkovaite leaves light blue, Apophyllite leaves white; luster reads vitreous on Zubkovaite and vitreous to pearly on Apophyllite.

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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-blue Turquoise Light 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

Look in alkaline pegmatites country, the host setting where zubkovaite typically forms. If you start seeing apophyllite, natrolite, aegirine in float, you are in the right ground. Field specimens usually show a prismatic or sometimes lath-like crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify zubkovaite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. 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?+

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 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?+

Zubkovaite typically forms in 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

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