Sylvanite Identification Guide

Identifying sylvanite, a silvery gold-silver telluride, by its metallic luster, branching crystal habit, softness, density, and how to separate it from calaverite and pyrite.

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What Sylvanite Looks Like

Sylvanite is a silver-gold telluride (AgAuTe4) and an important ore of gold. It has a bright metallic luster and a steely silver-white to brassy or pale yellow color, sometimes with a creamy tint. It commonly forms bladed, prismatic, or skeletal crystals that branch into distinctive arborescent (tree-like), feathery, or graphic patterns on rock surfaces, an appearance that gave rise to the term "graphic tellurium." It is opaque, brittle, and relatively heavy. Massive and granular forms also occur within quartz veins alongside gold and other tellurides.

Key Visual Cues

Bright metallic, silver-white to pale brassy-yellow
Branching, feathery, or graphic crystal aggregates
Opaque and brittle
Often in quartz veins with native gold

Step-by-Step Field ID Checklist

Note metallic color. Silvery-white to pale yellow metallic luster is typical.
Look for graphic patterns. Branching, dendritic, or skeletal growths are highly characteristic.
Test hardness. Sylvanite is soft, Mohs 1.5 to 2, and can be scratched by a copper coin or knife.
Check the streak. Steel-grey to silver-white streak.
Heft it. It feels heavy; specific gravity is high (~8).
Note brittleness. It breaks rather than bends, with one good cleavage direction.

Diagnostic Tests

Mohs hardness: 1.5 to 2, very soft.
Streak: steel-grey to silvery.
Cleavage: perfect in one direction.
Specific gravity: ~8.0 to 8.2, distinctly heavy.
Acid: decomposes/affected by hot nitric acid (telluride behavior).
Magnetism: non-magnetic.

Common Look-Alikes and How to Tell Them Apart

Calaverite: another gold telluride, but calaverite is more brassy-yellow and lacks the silver-white tint and graphic branching of sylvanite; precise distinction often needs lab analysis, but sylvanite's silvery color and graphic habit help.
Pyrite: pyrite is much harder (6 to 6.5), pale brassy, and forms cubes/pyritohedrons; sylvanite is soft (under 2) and heavier. A scratch test separates them instantly.
Native gold: gold is malleable (dents, does not shatter), deeper yellow, and lacks cleavage; sylvanite is brittle and silvery.
Galena: galena is lead-grey with perfect cubic cleavage and a higher silver-grey sheen; sylvanite shows graphic branching and different cleavage.
Marcasite/arsenopyrite: both are harder and paler; hardness and density distinguish them from soft, heavy sylvanite.

Where Sylvanite Is Found

Sylvanite occurs in low-temperature gold-silver hydrothermal vein deposits, often associated with quartz, native gold, calaverite, krennerite, and other tellurides. Classic localities include the Transylvania region of Romania (from which it takes its name), Kalgoorlie in Western Australia, Cripple Creek in Colorado (USA), and various epithermal gold districts. It is mined as a valuable gold (and silver) ore where tellurides are abundant.

Frequently asked questions

How can you tell if it's real sylvanite?

Sylvanite is a soft (Mohs 1.5 to 2), heavy (SG ~8), brittle metallic mineral with a silver-white to pale yellow color, a steel-grey streak, one perfect cleavage, and often distinctive branching graphic crystal patterns. Its softness and high density separate it from pyrite and gold.

What does sylvanite look like?

It looks like a bright metallic, silvery-white to pale brassy mineral that often forms feathery, branching, or graphic crystal patterns on rock, typically within gold-bearing quartz veins.

Sylvanite vs pyrite, how do you tell them apart?

Pyrite is hard (6 to 6.5), forms cubes, and is brassy, while sylvanite is very soft (under 2), heavier, brittle, and silver-white with graphic branching. A simple scratch test, pyrite resists a knife and sylvanite does not, is decisive.

Is sylvanite a gold ore?

Yes. Sylvanite is a silver-gold telluride and an important ore of gold, mined in telluride-rich epithermal deposits such as those at Cripple Creek, Colorado and Kalgoorlie, Australia.

How is sylvanite different from native gold?

Native gold is malleable and dents when pressed, has a deep yellow color, and no cleavage, while sylvanite is brittle, shatters, is more silvery, and has one perfect cleavage direction.