sedimentary
Hematite Nodules (Moqui Marbles style)
Iron Oxide (Fe2O3)
Hardness: 5.5-6.5; Color: Metallic grey to black; Luster: Metallic to sub-metallic; Crystal structure: Trigonal; Specific gravity: 5.26
- Hardness
- 5
- Color
- Metallic grey to black
- Luster
- Metallic to sub-metallic
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Physical properties
Hardness: 5.5-6.5; Color: Metallic grey to black; Luster: Metallic to sub-metallic; Crystal structure: Trigonal; Specific gravity: 5.26
Formation & geological history
Formed by the precipitation of iron-rich groundwater through porous sandstone, often during the Jurassic period in the Navajo Sandstone of the American Southwest.
Uses & applications
Used as an ore of iron, in jewelry as beads/cabochons, and as a popular 'talisman' or grounding stone in spiritual circles.
Geological facts
These are often called 'Moqui Marbles' and are famous for their spherical or disc-like shapes. Similar structures have been discovered on Mars, known as 'Blueberries'.
Field identification & locations
Identified by their metallic grey appearance and high density. The most definitive test is a 'streak test'—rubbing it on unglazed porcelain will leave a characteristic rust-red streak.
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