sedimentary
Agate (River Pea)
Microcrystalline Chalcedony (SiO2)
Hardness: 6.5–7 on the Mohs scale. Color: Translucent honey-yellow to brownish-orange. Luster: Waxy to vitreous. Crystal structure: Trigonal/Microcrystalline. Specific gravity: 2.60–2.64.
- Hardness
- 6
- Color
- Translucent honey-yellow to brownish-orange
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5–7 on the Mohs scale. Color: Translucent honey-yellow to brownish-orange. Luster: Waxy to vitreous. Crystal structure: Trigonal/Microcrystalline. Specific gravity: 2.60–2.64.
Formation & geological history
Formed in volcanic cavities or sedimentary pockets where silica-rich groundwater deposits layers over thousands of years. This specimen has been naturally tumbled and rounded by river or alluvial action over geological time.
Uses & applications
Used in lapidary work for cabochons and beads, industrial mortars and pestles due to its hardness, and highly valued by rockhounds for tumbling and aesthetic collecting.
Geological facts
Agates are traditionally associated with healing and strength. Many river-found agates in the Pacific Northwest are known as 'Carnelian' when they exhibit this specific warm, translucent orange hue.
Field identification & locations
Identify in the field by checking for translucency against the sun (backlighting) and a smooth, waxy feel compared to surrounding dull rocks. Commonly found on riverbanks, gravel bars, and beaches.
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