Stranskiite is a rare secondary mineral found almost exclusively in the world-famous Tsumeb Mine in Namibia. It typically appears as striking azure-blue, thin tabular crystals or crystalline crusts associated with other rare zinc and copper arsenates.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

Light Blue

Transparency

Transparent

mineralrare

Stranskiite

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

Is this stranskiite?

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 stranskiite with a known reference. Stranskiite 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. Stranskiite leaves a light blue streak.
3
Read the luster
Hold the specimen under a strong light. Stranskiite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: azure-blue, sky-blue.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, crusts.

Often confused with

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

mineral

Lavendulan

Mohs 2.5

How to tell apart: Stranskiite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs — Stranskiite leaves light blue, Lavendulan leaves pale blue.

Compare →

Often found alongside stranskiite

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

All properties

Chemical formula: Zn₂Cu(AsO₄)₂
Mohs hardness: 3.5
Density: 5.38 g/cm³
Colors: Azure-blue Sky-blue
Streak: Light Blue
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular Crystals, Crusts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Polymetallic Ore Deposits
Typical price: $100-500 thumbnail

Where rockhounds find stranskiite

Classic worldwide localities

Tsumeb Mine, Tsumeb, Namibia

Field-hunting tip

Look in hydrothermal polymetallic ore deposits country — that is the host setting where stranskiite typically forms. If you start seeing tsumcorite, tennantite, adamite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify stranskiite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is light blue. Common colors include azure-blue, sky-blue.

Where is stranskiite found?+

Notable localities include Tsumeb Mine, Tsumeb, Namibia.

How much is stranskiite worth?+

Typical asking prices fall in the range of $100-500 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

Is stranskiite safe to handle?+

It contains toxic constituents. Contains arsenic and copper; avoid ingestion, inhalation of dust, or prolonged skin contact. Wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like stranskiite?+

Stranskiite is most often confused with Lavendulan. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with stranskiite?+

Stranskiite commonly co-occurs with Tsumcorite, Tennantite, Adamite, Willemite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does stranskiite form in?+

Stranskiite typically forms in hydrothermal polymetallic ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is stranskiite used for?+

Stranskiite is used in collector.

Find stranskiite on the map

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