mineral
Chalcedony (Yellow Chert / Agate)
Quartz (Silicon Dioxide - SiO2)
Hardness of 6.5-7 on Mohs scale, waxy to vitreous luster, translucent yellowish-brown to amber color, microcrystalline (cryptocrystalline) structure, conchoidal fracture.
Identified More mineral →
Explore Chalcedony (Yellow Chert / Agate) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness of 6.5-7 on Mohs scale, waxy to vitreous luster, translucent yellowish-brown to amber color, microcrystalline (cryptocrystalline) structure, conchoidal fracture.
Formation & geological history
Forms by precipitation of silica from aqueous solutions, commonly in volcanic cavities or sedimentary gravel deposits as stream-rounded nodules.
Uses & applications
Used for lapidary arts, beads, carvings, tumbled gemstones, and ornamental collections.
Geological facts
Cryptocrystalline quartz varieties like chalcedony and agate have been used since prehistoric times for making tools, arrowheads, and jewelry due to their durability and sharp conchoidal fracture.
Field identification & locations
Identified in the field by its smooth, waxy surface, light translucency when held to the sun, absence of cleavage, and resistance to steel scratching. Widely found in river beds, gravel deposits, and alluvial fields.
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