Goldschmidtite is a rare potassium gold telluride mineral discovered as inclusions within diamonds from the Koffiefontein pipe. It represents a unique geochemical signature of mantle conditions where gold and tellurium are trapped deep within the Earth's interior.

Hardness

3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Goldschmidtite

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

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Is this goldschmidtite?

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 goldschmidtite with a known reference. Goldschmidtite 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. Goldschmidtite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Goldschmidtite 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: cubic. Typical habit: anhedral to subhedral grains.

Often confused with

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

mineral

Sylvanite

Mohs 1.5-2

How to tell apart: Goldschmidtite is noticeably harder (Mohs 3.5 vs. 1.5-2); streak differs — Goldschmidtite leaves black, Sylvanite leaves gray.

How to tell apart: Streak differs — Goldschmidtite leaves black, Calaverite leaves yellowish-green.

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Often found alongside goldschmidtite

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

All properties

Chemical formula: KAuTe₄
Mohs hardness: 3.5
Density: 8.52 g/cm³
Colors: Silver-white
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Anhedral to Subhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Kimberlite
Typical price: very high, research grade material

Where rockhounds find goldschmidtite

Classic worldwide localities

Koffiefontein mine, South Africa

Field-hunting tip

Look in kimberlite country — that is the host setting where goldschmidtite typically forms. If you start seeing diamond, phlogopite, enstatite in float, you are in the right ground. Field specimens usually show a anhedral to subhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify goldschmidtite?+

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

Where is goldschmidtite found?+

Notable localities include Koffiefontein mine, South Africa.

How much is goldschmidtite worth?+

Typical asking prices fall in the range of very high, research grade material. Quality, size, and provenance can move individual specimens well outside that range.

Is goldschmidtite safe to handle?+

It contains toxic constituents. Contains tellurium, which can release toxic fumes if heated or processed. Handle with care and avoid inhalation of dust or vapors. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like goldschmidtite?+

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

What minerals are found with goldschmidtite?+

Goldschmidtite commonly co-occurs with diamond, phlogopite, enstatite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does goldschmidtite form in?+

Goldschmidtite typically forms in kimberlite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is goldschmidtite used for?+

Goldschmidtite is used in collector.

Find goldschmidtite on the map

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