mineral

Agate Geode Slice (with Druzy Quartz)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Grayish-blue outer chalcedony with a yellowish-white crystalline center; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline (agate) with macrocrystalline quartz in the center; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65

Hardness: 6
Luster: Waxy to vitreous

Identified April 4, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed as secondary deposits in volcanic rock cavities (vesicles) or sedimentary pockets. Siliceous groundwater permeates the rock, slowly depositing layers of chalcedony over thousands of years. The central opening indicates it is part of a geode where crystals had space to grow inward.

Uses & applications

Primarily used for decorative purposes, gemstone collecting, metaphysical jewelry, and lapidary art.

Geological facts

Agate is named after the Achates River in Sicily. The concentric banding visible in such specimens is actually rhythmic layers of silica and impurities. The small, sparkling crystals in the center are known as 'druzy' quartz.

Field identification & locations

Identify in the field by looking for rounded, lumpy nodules with a rough, dull exterior that feels heavy for its size. High-quality pieces are typically sourced from Brazil, Uruguay, and Oregon, USA. This specific shape is a custom-cut and polished slab designed for display.

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