sedimentary

Jasper and Agate

Microcrystalline Quartz (SiO2)

Hardness: 6.5–7 (Mohs scale); Color: Creamy white, grey, beige, and yellow-brown; Luster: Waxy to vitreous; Crystal Structure: Trigonal/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Creamy white, grey, beige, and yellow-brown
Luster: Waxy to vitreous

Identified April 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of volcanic rocks or sedimentary layers. These specimens appear to be river-tumbled 'river stones' shaped by water erosion over thousands to millions of years.

Uses & applications

Commonly used for lapidary work, jewelry (cabochons), tumbling for decorative gravel, and as healing stones in metaphysical practices. Also used in industrial abrasives.

Geological facts

Jasper and agate are both varieties of chalcedony; the distinction is usually transparency—agate is translucent, while jasper is opaque. These smooth textures are the result of natural water tumbling or a mechanical rock tumbler.

Field identification & locations

Identify in the field by their smooth, rounded shapes in riverbeds or beaches, their high hardness (they can scratch glass), and their waxy feel. Commonly found in gravel bars of major river systems globally.