sedimentary

Moqui Marble (Ironstone Concretion)

Iron Oxide Concretion (Fe2O3)

AI-generated identification · may be incorrect

Hardness: 5-5.5 (outer shell); Color: Dark brown, black, rust-yellow; Luster: Dull, earthy, or sub-metallic; Crystal structure: Amorphous/microcrystalline; Specific Gravity: Approx 3.0-3.5

Hardness: 5-5
Color: Dark brown, black, rust-yellow
Luster: Dull, earthy, or sub-metallic

Identified June 26, 2026More sedimentary →

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Physical properties

Hardness: 5-5.5 (outer shell); Color: Dark brown, black, rust-yellow; Luster: Dull, earthy, or sub-metallic; Crystal structure: Amorphous/microcrystalline; Specific Gravity: Approx 3.0-3.5

Formation & geological history

Formed by the precipitation of iron oxide (hematite/goethite) around a nucleus within porous sandstone layers (Navajo Sandstone), typically during the Jurassic period (approx. 190 million years ago) through groundwater movement.

Uses & applications

Used primarily as metaphysical 'shaman stones' in New Age practices, educational specimens, and items for mineral collectors.

Geological facts

Native American legend suggests spirits of ancestors play games with these 'marbles' at night. Technically, they are concretions where iron-rich water cemented sand grains together.

Field identification & locations

Identify by their spherical shape and dark, hard iron-oxide rim with a sandy core. Commonly found in the American Southwest, particularly Utah and Arizona.