mineral
Polished agate (likely blue-gray chalcedony)
Microcrystalline quartz, SiO₂; chalcedony, possibly banded agate
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; glossy, waxy luster with translucent blue-gray and white areas. Quartz has a trigonal crystal structure, but its microscopic grains show no visible cleavage; the pictured piece appears tumbled or polished.
Identified More mineral →
Explore Polished agate (likely blue-gray chalcedony) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness 6.5–7 Mohs; glossy, waxy luster with translucent blue-gray and white areas. Quartz has a trigonal crystal structure, but its microscopic grains show no visible cleavage; the pictured piece appears tumbled or polished.
Formation & geological history
Silica-rich fluids deposited quartz in cavities, commonly in volcanic rock; agate formed by successive deposition and banding. Its precise age and locality cannot be determined from the image.
Uses & applications
Used for jewelry, beads, and decorative objects; agate is also used in small ornaments and lapidary work.
Geological facts
Agate is a variety of chalcedony, not a separate mineral species; its distinctive bands form as silica layers accumulate over time.
Field identification & locations
Look for translucency, waxy luster, hardness, and natural curved bands; common sources include Brazil, Uruguay, India, and the western United States.
More like this
Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Granite
Granite (Phaneritic intrusive igneous rock)
igneous