mineral

Chalcedony (including Carnelian and Agate variants)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Milky white, orange-red (carnelian), and yellow-translucent; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58–2.64

Hardness: 6
Color: Milky white, orange-red (carnelian), and yellow-translucent
Luster: Waxy to vitreous

Identified July 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich groundwater in cavities of volcanic and sedimentary rocks. They frequently occur as nodules or crusts in basaltic lava or as vein fillings.

Uses & applications

Used widely in jewelry (cabochons, beads), decorative carvings, and as a semi-precious gemstone. Historically used for making seals and amulets.

Geological facts

Carnelian (the reddish-orange variety shown) was highly prized in ancient Egypt and Rome for signet rings because hot wax does not stick to it. The white/clear piece is a standard chalcedony or quartz nodule.

Field identification & locations

Identify by its waxy luster, conchoidal fracture (curved breaks), and lack of visible crystal faces. Commonly found in riverbeds, gravel deposits, and volcanic regions globally.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

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

metamorphic

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock

Granite

Granite (Phaneritic intrusive igneous rock)

igneous