mineral
Agate (Carnelian / Chalcedony)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Hardness: 6.5-7 on Mohs scale; Color: Honey-yellow, translucent brown to orange; Luster: Waxy to vitreous; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64
- Hardness
- 6
- Color
- Honey-yellow, translucent brown to orange
- Luster
- Waxy to vitreous
Identified More mineral →
Explore Agate (Carnelian / Chalcedony) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Honey-yellow, translucent brown to orange; Luster: Waxy to vitreous; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64
Formation & geological history
Forms primarily within cavities (geodes) of volcanic igneous rocks or sedimentary formations as silica-rich water precipitates layer by layer over time.
Uses & applications
Popular for gemstone lapidary work, tumbling, jewelry making, ornamental carvings, and rock collecting.
Geological facts
Agates are microcrystalline varieties of quartz. The translucent honey-yellow to orange coloration is typically due to iron oxide impurities embedded within the silica matrix.
Field identification & locations
Look for a waxy, smooth texture, conchoidal fracture surfaces, high translucency under light, and a high hardness that scratches glass. Commonly found along gravel bars, riverbeds, and volcanic rock outcrops worldwide.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock