sedimentary

Sandstone Geode (Unbroken)

Siliciclastic sedimentary rock (primarily Quartz)

Hardness: 6.5-7 (Quartz based); Color: Tan, beige, or reddish-brown; Luster: Dull or earthy exterior; Crystal structure: Amorphous to massive exterior with potential internal macro-crystals; Cleavage: None; Specific Gravity: Approx 2.3-2.6

Hardness: 6
Color: Tan, beige, or reddish-brown
Luster: Dull or earthy exterior

Identified May 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed over millions of years through the precipitation of minerals into voids or cavities within sedimentary rock layers like sandstone or limestone. This specific specimen has been weather-rounded by water action.

Uses & applications

Geodes are used for education, home decor, and mineral collecting. If opened, they may contain quartz or calcite crystals with high ornamental value.

Geological facts

Geodes appear to be ordinary rocks on the outside, but when cracked open, they reveal a hollow cavity lined with sparkling crystals. The state of Iowa is famous for its 'Keokuk geodes'.

Field identification & locations

Identify by its light weight relative to size (if hollow), 'rattling' sound when shaken, and rounded, lumpy surface texture compared to standard river rocks. Found in desert regions, ash beds, or sedimentary outcroppings.

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