Native Gold

Description

Native Gold is a naturally occurring element and mineral, consisting almost entirely of the element gold (Au). It is highly prized for its distinctive metallic luster, golden-yellow color, extreme malleability, ductility, and resistance to corrosion. It typically occurs as small flakes, grains, wires, or nuggets, often disseminated in quartz veins or concentrated in placer deposits. Its high density is a key characteristic, making it easily separable from most other minerals.

How to Identify

Color

Bright golden-yellow, often with a slightly reddish or greenish tint depending on impurities (e.g., silver, copper).

Luster

Distinctive metallic luster, even when tarnished.

Texture

Smooth to slightly rough, often found as irregular grains, flakes, wires, or nuggets. Can be massive or dendritic.

Crystal Form

Cubic crystal system, but well-formed crystals are rare. Typically occurs as irregular masses, scales, wires, dendrites, or nuggets. Octahedral and dodecahedral forms are occasionally observed.

Cleavage

None. Gold is sectile and malleable, meaning it can be cut and hammered into thin sheets without breaking along planes.

Geological Environment

Primarily found in hydrothermal quartz veins associated with igneous and metamorphic rocks, often with sulfides (pyrite, arsenopyrite, galena, sphalerite). Also extensively found in placer deposits (alluvial, eluvial, and beach placers) derived from the erosion of primary gold-bearing rocks.

Key Facts

• Hardness: 2.5-3 on the Mohs scale
• Specific Gravity: 19.3 (pure gold); decreases with increasing silver content (electrum)
• Crystal System: Cubic (isometric)
• Color: Golden-yellow
• Luster: Metallic
• Transparency: Opaque
• Fracture: Hackly (jagged, sharp edges)
• Cleavage: None
• Composition: Elemental gold (Au), often with minor silver (Ag) and sometimes copper (Cu) or other metals.

Quick Check

• Color: Golden-yellow
• Luster: Metallic
• Streak: Golden-yellow

Physical Characteristics

• Crystal Habit: Typically anhedral masses, scales, flakes, wires, dendrites, or nuggets. Rarely forms distinct crystals (octahedra, dodecahedra, cubes).
• Cleavage Type: Absent
• Fracture Type: Hackly
• Tenacity: Malleable and ductile (can be hammered into thin sheets and drawn into wire without breaking). Sectile (can be cut with a knife).
• Luster Type: Metallic

Formation

Native gold forms primarily through hydrothermal processes, where hot, aqueous fluids carrying dissolved gold and other elements circulate through fractures and pores in rocks. As these fluids cool or react with the host rock, gold precipitates out. It can also form through metamorphic processes or, less commonly, magmatic processes. Placer deposits form when gold-bearing rocks erode, and the dense gold particles are concentrated by water currents in stream beds, rivers, and beaches.

Usage

Historically and currently, native gold is primarily used as a monetary standard, an investment, and in jewelry due to its beauty, rarity, and resistance to corrosion. Industrially, it is crucial in electronics (due to its excellent electrical conductivity and corrosion resistance), dentistry, medical applications, and as a catalyst in various chemical processes. Its high malleability and ductility also make it valuable for specialized applications.

Age Distribution

Found in rocks of all ages, from Precambrian to Cenozoic, wherever suitable geological conditions for its formation have occurred.

Where to Find

Finding Tips

Similar Rocks

Scientific Classification

Mineral Class

Native Elements

Group

Gold Group

Crystal System

Cubic (Isometric)

Chemical Formula

Au

Composition

Pure gold (Au), often with varying amounts of silver (Ag) forming electrum (Au,Ag alloy), and sometimes traces of copper (Cu), iron (Fe), or platinum group elements (PGEs).

Explore Native Gold