gemstone

Agate (Carnelian / Yellow Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Yellowish-orange to translucent amber; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline/cryptocrystalline quartz); Cleavage: None; Conchoidal fracture; Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Yellowish-orange to translucent amber
Luster: Waxy to vitreous

Identified July 25, 2026More gemstone →

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Physical properties

Formation & geological history

Forms in cavities within volcanic or metamorphic rocks when silica-rich fluids deposit layers of chalcedony over extended geological periods. Often eroded into coastal sediments and river gravels.

Uses & applications

Used in lapidary arts, jewelry making (cabochons, beads), decorative carvings, and as popular beachcombing collectibles.

Geological facts

Agates and chalcedony pebbles are often tumbled smooth by natural ocean surf and river currents, developing a soft, semi-translucent, waxy surface sheen.

Field identification & locations

Look for a translucent appearance when backlit, smooth rounded shapes, and a waxy luster on beach sands or river beds. Extremely common along Pacific Coast and Baltic beaches.

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Diamond and Gold Jewelry

Carbon (Diamond) / Au (Gold)

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Ammolite

Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)

mineral

Cubic Zirconia (simulant) or Diamond

ZrO2 (Cubic Zirconia) or C (Diamond)

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Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

sedimentary

Cubic Zirconia (or possibly Diamond)

Zirconium dioxide (or Carbon)

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Faceted Gemstone

Unknown transparent mineral, possibly Diamond (C), Cubic Zirconia (ZrO2), Quartz (SiO2), or Glass

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