Gruzdevite is a rare mercury-copper sulfosalt known primarily from the Khaydarkan deposit in Kyrgyzstan. It typically occurs as microscopic, grey metallic grains embedded within other sulfide minerals, making it a challenging species for field identification without analytical methods.

Hardness

3-3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Gruzdevite

Hardness: 3-3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

No image

Is this gruzdevite?

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 gruzdevite with a known reference. Gruzdevite sits at Mohs 3-3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Gruzdevite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Gruzdevite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: gray, white.
5
Look at form & habit
Crystal system: trigonal. Typical habit: anhedral grains.

Often confused with

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

Often found alongside gruzdevite

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

All properties

Chemical formula: Cu₆Hg₃Sb₄S₁₂
Mohs hardness: 3-3.5
Density: 5.34 g/cm³
Colors: Gray White
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Trigonal
Crystal habit: Anhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Mercury-antimony Deposits
Typical price: $50-300 per specimen

Where rockhounds find gruzdevite

Classic worldwide localities

Khaydarkan mercury deposit, Kyrgyzstan

Field-hunting tip

Look in hydrothermal mercury-antimony deposits country — that is the host setting where gruzdevite typically forms. If you start seeing cinnabar, calcite, quartz in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify gruzdevite?+

Mohs hardness is 3-3.5. It typically shows a metallic luster. The streak is black. Common colors include gray, white.

Where is gruzdevite found?+

Notable localities include Khaydarkan mercury deposit, Kyrgyzstan.

How much is gruzdevite worth?+

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

Is gruzdevite safe to handle?+

It contains toxic constituents. Contains mercury and antimony; avoid creating dust, wash hands thoroughly after handling, and store in a sealed container. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like gruzdevite?+

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

What minerals are found with gruzdevite?+

Gruzdevite commonly co-occurs with Cinnabar, Calcite, Quartz, Stibnite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does gruzdevite form in?+

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

What is gruzdevite used for?+

Gruzdevite is used in collector.

Find gruzdevite on the map

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