mineral
Agate nodule (cross-section)
Microcrystalline quartz (SiO₂), a banded variety of chalcedony
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; brown, gray, and cream concentric bands with a waxy to vitreous luster. Trigonal quartz in microscopic fibers; no distinct cleavage, conchoidal fracture; specific gravity about 2.6.
Identified More mineral →
Explore Agate nodule (cross-section) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness 6.5–7 Mohs; brown, gray, and cream concentric bands with a waxy to vitreous luster. Trigonal quartz in microscopic fibers; no distinct cleavage, conchoidal fracture; specific gravity about 2.6.
Formation & geological history
Silica-rich fluids deposited successive layers in a cavity, likely in volcanic rock; the exact age and locality cannot be determined from the image.
Uses & applications
Used for lapidary, jewelry, ornaments, and collectible specimens; agate is also used in precision components and abrasives.
Geological facts
Agate’s bands record changes in silica deposition, and some apparent banding can form around cavity walls.
Field identification & locations
Look for curved, concentric bands and a hard, glassy-to-waxy surface; commonly occurs in volcanic rocks and river gravels worldwide. Estimated value: about $2–$20 for a small, ordinary cut nodule; more if polished or unusually patterned.
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
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous