Chursinite is a very rare calcium arsenate mineral typically found in the oxidation zones of antimony-mercury deposits. It usually forms as small, colorless to pale yellow tabular crystals or crusts that are easily confused with common minerals like gypsum.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Chursinite

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this chursinite?

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 chursinite with a known reference. Chursinite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Chursinite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Chursinite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, pale yellow.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, massive, crusts.

Often confused with

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

Often found alongside chursinite

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

All properties

Chemical formula: Ca₂(AsO₄)(OH)
Mohs hardness: 2
Density: 3.37 g/cm³
Colors: Colorless White Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Massive, Crusts
Cleavage: Perfect On {010}
Rarity: Rare
Uses: Collector
Host rock: Low-temperature Hydrothermal Deposits
Typical price: $50-300 per small specimen

Where rockhounds find chursinite

Classic worldwide localities

Khaidarkan Sb-Hg deposit, Kyrgyzstan

Field-hunting tip

Look in low-temperature hydrothermal deposits country — that is the host setting where chursinite typically forms. If you start seeing pharmacolite, calcite, realgar in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify chursinite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, pale yellow.

Where is chursinite found?+

Notable localities include Khaidarkan Sb-Hg deposit, Kyrgyzstan.

How much is chursinite worth?+

Typical asking prices fall in the range of $50-300 per small specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is chursinite safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic. Avoid creating dust and wash hands thoroughly after handling specimens. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like chursinite?+

Chursinite is most often confused with Gypsum, Pharmacolite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with chursinite?+

Chursinite commonly co-occurs with Pharmacolite, Calcite, Realgar, Orpiment. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does chursinite form in?+

Chursinite typically forms in low-temperature hydrothermal deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is chursinite used for?+

Chursinite is used in collector.

Find chursinite on the map

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