mineral

Gold (10K Alloy)

Aurum (Au) with alloying metals (Cu, Ag, Zn)

Hardness: 2.5–3 (pure) to ~3.5-4 (10k alloy); Color: Yellow; Luster: Metallic; Crystal Structure: Isometric; Specific Gravity: ~11.0-11.5 for 10k

Hardness: 2
Color: Yellow
Luster: Metallic

Identified March 24, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 2.5–3 (pure) to ~3.5-4 (10k alloy); Color: Yellow; Luster: Metallic; Crystal Structure: Isometric; Specific Gravity: ~11.0-11.5 for 10k

Formation & geological history

Native gold forms in hydrothermal quartz veins or placer deposits. The specimen shown is a processed 10-karat alloy (41.7% gold) manufactured for jewelry components like earring backs.

Uses & applications

Primary use in jewelry manufacturing (earring findings), dentistry, and electronic connectors due to corrosion resistance.

Geological facts

The label '10K' indicates that the item consists of 10 parts gold and 14 parts other metals. Pure gold is too soft for functional jewelry parts like screw-back earrings, so it is alloyed for durability.

Field identification & locations

Identify by '10K' or '417' stamps on the metal. It is highly resistant to tarnish compared to base metals. Found globally in lode deposits (California, South Africa, Australia) before refining.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral