Rock Identifier
Moss Agate (Silicon Dioxide (SiO2) with inclusions of hornblende, chlorite, or manganese/iron oxides) — mineral
mineral

Moss Agate

Silicon Dioxide (SiO2) with inclusions of hornblende, chlorite, or manganese/iron oxides

Hardness: 6.5–7 on Mohs scale; Color: Translucent to milky white with green, dendritic (moss-like) or filament-like inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.64

Hardness
6
Luster
Vitreous to waxy
Identified More mineral →

Identify your own rocks.

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

App StoreGoogle Play

Physical properties

Hardness: 6.5–7 on Mohs scale; Color: Translucent to milky white with green, dendritic (moss-like) or filament-like inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.64

Formation & geological history

Formed through the deposition of silica in cavities of igneous rocks (volcanic basalt). The 'moss' patterns are formed by mineral oxides (such as iron or manganese) entering the silica gel during its cooling and hardening process over millions of years.

Uses & applications

Primarily used in jewelry (cabochons, beads, and pendants), decorative ornaments, and as a popular specimen for collectors. In historical times, it was used as a talisman and for horticultural charms.

Geological facts

Despite its name, Moss Agate does not contain organic plant matter; the 'moss' is purely mineral. It is often referred to as a 'Mocha stone' and has been used throughout history since antiquity, particularly in European jewelry from the 18th century.

Field identification & locations

Identify in the field by looking for a semi-translucent quartz-like stone that contains dark green branching patterns. Common locations include India, Brazil, the United States (specifically Montana), and parts of Central Europe. For collectors, higher translucency and more intricate 'branching' patterns increase value.

More like this

Other mineral specimens

Sandstone (with potential mineral staining/concretions) (Arenite (SiO2 based)) — sedimentary

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

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

Epidote

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

metamorphic
Nephrite Jade (Nephrite) — Mineral/Rock

Nephrite Jade

Nephrite

Mineral/Rock
Banded Gneiss (River Rock/Pebble) (Gneiss (specifically a banded variety often found as a river rock)) — Metamorphic 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

Green Apatite on Albite

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

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

Epidote

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

mineral