mineral

Agate (Moss or Lake Superior type)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Hardness: 6.5-7 (Mohs scale); Color: Variegated brown, orange, black, and translucent grey; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Variegated brown, orange, black, and translucent grey
Luster: Waxy to vitreous

Identified April 16, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Variegated brown, orange, black, and translucent grey; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture).

Formation & geological history

Formed in cavities (vesicles) of volcanic lava flows, such as those that occurred over 1 billion years ago in the Midcontinent Rift System. Ground water rich in silica seeped into bubbles and hardened over time, creating layers.

Uses & applications

Used primarily for lapidary work (jewelry, cabochons), decor, and as popular collectibles for rockhounds.

Geological facts

Agates are known for their banded patterns and translucency. The Lake Superior Agate is the state gem of Minnesota and is prized for its iron-rich red and orange colors.

Field identification & locations

Look for a waxy, 'plastic-like' texture and pitted surfaces. Translucency when held up to a bright light is a primary identification tool in the field. Found in gravel pits and along shorelines.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

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