sedimentary

Quartz Geode Pebble

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: White to translucent with green staining (likely algae or weathering). Luster: Vitreous to dull. Crystal structure: Trigonal (microcrystalline chalcedony outer layer with macrocrystalline quartz center). Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Luster: Vitreous to dull

Identified August 1, 2026More sedimentary →

Explore Quartz Geode Pebble in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed in sedimentary environments where silica-rich groundwater fills cavities in host rock (such as limestone or basalt), precipitating microcrystalline chalcedony on the outer rim and growing sparkling quartz crystals inward over millions of years.

Uses & applications

Used primarily as a decorative specimen, in lapidary arts, wire-wrapping, and as a popular find for rockhounds and amateur collectors.

Geological facts

Quartz is one of the most abundant minerals on Earth's continental crust. When a void in a rock is completely filled rather than hollow, it is technically an agate nodule, but when a central cavity remains lined with crystals, it is a geode.

Field identification & locations

Easily identified by its characteristic rounded, water-worn pebble shape combined with a central patch of sparkling micro-crystals. Common in riverbeds and gravel bars worldwide where resistant quartz has survived weathering and erosion.