Belendorffite is a rare copper-mercury amalgam found in oxidized zones of mercury deposits. It typically occurs as minute, silver-white metallic grains or small aggregates associated with native mercury and cinnabar.

Hardness

3.5

Mohs

Luster

Metallic

Streak

Silver-white

Transparency

Opaque

mineralrareAmalgam family

Belendorffite

Hardness: 3.5
Luster: Metallic
Streak: Silver-white
Transparency: Opaque

Is this belendorffite?

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 belendorffite with a known reference. Belendorffite 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. Belendorffite leaves a silver-white streak.
3
Read the luster
Hold the specimen under a strong light. Belendorffite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: silver-white.
5
Look at form & habit
Crystal system: trigonal. Typical habit: irregular grains, small masses.

Often confused with

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

How to tell apart: Streak differs — Belendorffite leaves silver-white, Native Mercury leaves none.

Compare →

Often found alongside belendorffite

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

All properties

Chemical formula: Cu₇Hg₆
Mohs hardness: 3.5
Density: 13.6-13.8 g/cm³
Colors: Silver-white
Streak: Silver-white
Luster: Metallic
Transparency: Opaque
Crystal system: Trigonal
Crystal habit: Irregular Grains, Small Masses
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Mercury Deposits
Typical price: $50-300+ per specimen depending on size and rarity

Where rockhounds find belendorffite

Classic worldwide localities

Moschellandsberg, Germany
Rudnik, Serbia
Terlingua, Texas, USA

Field-hunting tip

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

Common questions

How do you identify belendorffite?+

Mohs hardness is 3.5. It typically shows a metallic luster. The streak is silver-white. Common colors include silver-white.

Where is belendorffite found?+

Notable localities include Moschellandsberg, Germany; Rudnik, Serbia; Terlingua, Texas, USA.

How much is belendorffite worth?+

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

Is belendorffite safe to handle?+

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

What rocks look like belendorffite?+

Belendorffite is most often confused with Potarite, Native Mercury. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with belendorffite?+

Belendorffite commonly co-occurs with Mercury, Cinnabar, Calcite, Dolomite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does belendorffite form in?+

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

What is belendorffite used for?+

Belendorffite is used in collector.

Find belendorffite on the map

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