sedimentary
Moqui Marble (Iron Concretion)
Iron Oxide Concretion (Goethite/Hematite Cemented Sandstone)
Hardness: 5.0-5.5 (outer shell); Color: Dark brown, rusty orange, or tan; Luster: Dull/Earthy; Structure: Spherical to subspherical; Specific Gravity: Approx. 3.0-4.0.
- Hardness
- 5
- Color
- Dark brown, rusty orange, or tan
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5.0-5.5 (outer shell); Color: Dark brown, rusty orange, or tan; Luster: Dull/Earthy; Structure: Spherical to subspherical; Specific Gravity: Approx. 3.0-4.0.
Formation & geological history
Formed roughly 2 to 25 million years ago via precipitation of iron oxide from groundwater flowing through porous Jurassic-age Navajo Sandstone. The iron collects around a central nucleus, cementing sand grains together.
Uses & applications
Primarily used as metaphysical 'shaman stones,' educational geological specimens, and for rock collecting. They are protected in national parks but sold legally from private land.
Geological facts
They are often compared to the 'Blueberries' found on Mars by the Opportunity rover, which are hematite concretions suggesting a watery past on the red planet. Their name comes from the Hopi word 'Moqui,' meaning 'dearly departed.'
Field identification & locations
Identify in the field by their rounded shape and dark, heavy iron crust contrasting with lighter surrounding sandstone. Commonly found in the American Southwest (Utah and Arizona). Collectors should look for symmetry and unbroken shells.
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