mineral

Chalcedony (Agate/Jasper mix)

Cryptocrystalline Sillimanite (Quartz) - SiO2

Hardness: 6.5-7 on Mohs scale. Color: Yellow-orange to milky white when backlit. Luster: Waxy to vitreous. Crystal structure: Hexagonal (trigonal) cryptocrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Yellow-orange to milky white when backlit
Luster: Waxy to vitreous

Identified June 27, 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 from the deposition of silica from groundwater in cavities of igneous rocks or through sedimentary processes. Often associated with volcanic environments where silica-rich fluids cool and solidify over thousands of years.

Uses & applications

Used primarily in lapidary arts for jewelry, carvings, and tumbled stones. Historically used for making tools and weapons due to its sharpness and toughness. Also popular for decorative metaphysical displays.

Geological facts

The term 'chalcedony' comes from the ancient Greek town of Chalcedon. When it shows banding, it is called Agate; when it is opaque and colorful, it is Jasper. This specific specimen exhibits high translucency, typical of high-quality quartz-based minerals.

Field identification & locations

Identify in the field by checking for a waxy texture, conchoidal (shell-like) fractures, and its ability to scratch glass. It is commonly found in riverbeds, desert pavements, and volcanic regions. It remains one of the most common yet diverse minerals for collectors.

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