mineral

Botryoidal Chalcedony in Geode/Vug

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Waxy tan to brownish-yellow interior; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Waxy tan to brownish-yellow interior
Luster: Waxy to vitreous

Identified May 26, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed by the low-temperature deposition of silica-rich groundwater within cavities of volcanic or sedimentary rocks. The botryoidal (grape-like) texture occurs as mineral layers grow outward from multiple nuclei simultaneously.

Uses & applications

Commonly used as a semi-precious gemstone in jewelry (cabochons), for decorative carvings, and as popular specimens for mineral collectors.

Geological facts

The term 'botryoidal' comes from the Greek word 'botrys,' meaning a bunch of grapes. Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen under a standard microscope.

Field identification & locations

Identify in the field by its waxy luster, rounded bubble-like surface, and hardness (it will scratch glass). Commonly found in desert regions, volcanic ash beds, and inside geodes or hollowed agates.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral