mineral

Carnelian and Mixed Agates

Cryptocrystalline Quartz (SiO2 with Iron Oxide impurities)

Hardness: 6.5-7 (Mohs scale), Color: Oranges, reds, browns, and translucent grays, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline), Cleavage: None/Conchoidal fracture, SG: 2.58-2.64

Hardness: 6

Identified July 4, 2026More mineral →

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Physical properties

Formation & geological history

Found within volcanic and sedimentary rocks where silica-rich groundwater fills cavities (vugs) or veins. Most are from the Quaternary or Tertiary periods, often weathered out of basalt.

Uses & applications

Used in jewelry, lapidary arts, metaphysical practices, and historical seal stones and amulets.

Geological facts

Carnelian is colored by iron oxide impurities. It was highly prized in ancient times, particularly by the Egyptians for protective amulets and Romans for signet rings because hot wax doesn't stick to it.

Field identification & locations

Identify in the field by its translucency, waxy luster, and lack of visible crystals. Often found in riverbeds, gravel pits, or beaches in volcanic regions.

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