sedimentary
Moqui Marble (Moqui Ball)
Ironstone Concretion (Goethite/Hematite cemented Sandstone)
Hardness: 5-5.5 (outer shell); Color: Rusty brown, chocolate brown to black; Luster: Dull, earthy, or metallic; Structure: Spherical to discoidal concretion; Cleavage: None; Specific Gravity: ~3.0-4.0 (depending on iron concentration).
- Hardness
- 5-5
- Color
- Rusty brown, chocolate brown to black
- Luster
- Dull, earthy, or metallic
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Physical properties
Hardness: 5-5.5 (outer shell); Color: Rusty brown, chocolate brown to black; Luster: Dull, earthy, or metallic; Structure: Spherical to discoidal concretion; Cleavage: None; Specific Gravity: ~3.0-4.0 (depending on iron concentration).
Formation & geological history
Formed during the Jurassic period (~180-140 million years ago) within the Navajo Sandstone. They are created by the precipitation of iron oxide (hematite or goethite) from groundwater circulating through porous sandstone, often forming around a nucleus.
Uses & applications
Primarily used as metaphysical or meditation stones, collected as geological curiosities, and displayed in educational mineral collections. Some historical use as children's marbles or grinding stones.
Geological facts
Also known as Shaman stones. 'Moqui' is a name formerly used for the Hopi people. Similar iron-oxide concretions discovered on Mars by the Opportunity rover are famously called 'blueberries,' providing evidence of past water on the red planet.
Field identification & locations
Identify in the field by their distinct round shape, dark pitted iron exterior, and sandstone interior if broken. Commonly found in the American Southwest (specifically Utah). Note: Many are located on protected land (like National Parks) where collecting is strictly prohibited.
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