sedimentary
Moqui Marble
Ironstone Concretion (Limonite/Hematite over Sandstone)
Hardness: 5-5.5 (outer shell); Color: Dark brown to black exterior, tan interior; Luster: Dull to sub-metallic; Crystal Structure: Amorphous/Microcrystalline; High specific gravity.
- Hardness
- 5-5
- Color
- Dark brown to black exterior, tan interior
- Luster
- Dull to sub-metallic
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Physical properties
Hardness: 5-5.5 (outer shell); Color: Dark brown to black exterior, tan interior; Luster: Dull to sub-metallic; Crystal Structure: Amorphous/Microcrystalline; High specific gravity.
Formation & geological history
Formed in the Navajo Sandstone (approximately 180-190 million years old) through the precipitation of iron-rich groundwater around a nucleus.
Uses & applications
Primarily collected as geological curiosities, used in metaphysical practices, and studied for planetary science as they are terrestrial analogs to 'blueberries' on Mars.
Geological facts
They are named after the Hopi tribe (formerly called Moqui). Similar iron concretions found by the Opportunity rover on Mars suggest past water activity on the red planet.
Field identification & locations
Identified by their round shape, heavy weight, and dark sandy texture. Commonly found in the American Southwest, particularly southern Utah.
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