Vasilyevite is a very rare mercury oxyhalide mineral known primarily from the Khaidarkan deposit in Kyrgyzstan. It typically occurs as small, resinous to adamantine platy crystals associated with other secondary mercury minerals in oxidized ore zones.

Hardness

2-3

Mohs

Luster

Adamantine

Streak

Red-brown

Transparency

Translucent

mineralrare

Vasilyevite

Hardness: 2-3
Luster: Adamantine
Streak: Red-brown
Transparency: Translucent

No image

Is this vasilyevite?

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 vasilyevite with a known reference. Vasilyevite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Vasilyevite leaves a red-brown streak.
3
Read the luster
Hold the specimen under a strong light. Vasilyevite typically shows a adamantine luster.
4
Match the color range
Compare against the expected color range: silvery gray, black, dark red- black.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals, granular aggregates.

Often confused with

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

mineral

Eglestonite

Mohs 2.5

How to tell apart: Streak differs, so Vasilyevite leaves red-brown, Eglestonite leaves yellowish-white.

How to tell apart: Streak differs, so Vasilyevite leaves red-brown, Kleinite leaves sulfur-yellow.

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Often found alongside vasilyevite

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

All properties

Chemical formula: (Hg²⁺₃O₂)₄Cl₂I₂
Mohs hardness: 2-3
Density: 9.57 g/cm³
Colors: Silvery Gray Black Dark Red- Black
Streak: Red-brown
Luster: Adamantine
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Platy Crystals, Granular Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Mercury Deposits

Where rockhounds find vasilyevite

Classic worldwide localities

Clear Creek mercury mine, New Idria district, San Benito County, California, USA

Field-hunting tip

Look in hydrothermal mercury deposits country, the host setting where vasilyevite typically forms. If you start seeing cinnabar, calomel, khaidarkanite in float, you are in the right ground. Field specimens usually show a platy crystals, granular aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify vasilyevite?+

Mohs hardness is 2-3. It typically shows a adamantine luster. The streak is red-brown. Common colors include silvery gray, black, dark red- black.

Where is vasilyevite found?+

Notable localities include Clear Creek mercury mine, New Idria district, San Benito County, California, USA.

Is vasilyevite safe to handle?+

It contains toxic constituents. Contains mercury; handle with extreme care, wash hands after handling, avoid ingestion or inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like vasilyevite?+

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

What minerals are found with vasilyevite?+

Vasilyevite commonly co-occurs with Cinnabar, Calomel, Khaidarkanite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does vasilyevite form in?+

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

What is vasilyevite used for?+

Vasilyevite is used in collector.

Find vasilyevite on the map

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