mineral

Raw Agate (Chalcedony Nodule)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Hardness: 6.5-7 on Mohs scale; Color: Honey-orange, amber, reddish-brown with white weathered exterior skin; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline/cryptocrystalline); Cleavage: None, exhibits conchoidal fracture; Specific Gravity: 2.58-2.64

Hardness: 6
Luster: Waxy to vitreous

Identified July 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed via secondary deposition of silica-rich solutions within cavity pockets (vesicles) of volcanic igneous rocks or sedimentary host rocks. As weathering dissolves surrounding matrix, durable agate nodules remain in alluvial gravels.

Uses & applications

Used in jewelry, lapidary arts, decorative cabochons, carved ornaments, and collected as raw rock specimens. Highly valued by tumbling enthusiasts.

Geological facts

Agate nodules often form distinct banded patterns inside. The rough, pitted chalky-white outer skin (cortex) is typical of stream-tumbled or weathered agate nodules found in arid or riverbed environments.

Field identification & locations

Identified by its waxy luster on exposed fractures, chalcedony hardness (scratches glass), translucent honey-amber interior glow under strong light, and rounded nodular shape. Commonly found in riverbeds, desert pavements, and volcanic region soils.

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