sedimentary
Ironstone Concretion (Moqui Marble type)
Iron oxide concretion (Goethite/Hematite and Sandstone)
Hardness: 5.0-6.0; Color: Dark brown to mocha or black exterior; Luster: Dull to earthy/metallic; Crystal structure: Amorphous/massive; Specific gravity: 3.4-4.2.
- Hardness
- 5
- Color
- Dark brown to mocha or black exterior
- Luster
- Dull to earthy/metallic
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Physical properties
Hardness: 5.0-6.0; Color: Dark brown to mocha or black exterior; Luster: Dull to earthy/metallic; Crystal structure: Amorphous/massive; Specific gravity: 3.4-4.2.
Formation & geological history
Formed by the precipitation of iron oxide minerals around a nucleus (often sand) within sedimentary rock layers, typically sandstone. Often associated with Jurassic-aged formations like the Navajo Sandstone.
Uses & applications
Used primarily as decorative collector pieces, metaphysical 'energy stones', and occasionally crushed for pigment.
Geological facts
Commonly known as Moqui Marbles or Shaman Stones, these spherical formations are often found in the American Southwest and have been at the center of geological research regarding similar hematite 'blueberries' found on Mars.
Field identification & locations
Identify by its spherical to sub-spherical shape, heavy weight for its size (due to iron content), and dark, durable exterior. Often found weathered out of sandstone cliffs in arid environments.
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