mineral

Hematite Concretion

Iron(III) oxide (Fe2O3)

Hardness: 5.5-6.5 Mohs; Color: reddish-brown to grey; Luster: metallic to earthy; Crystal Structure: Trigonal (often found in botryoidal or concretionary forms); Specific Gravity: 5.26.

Hardness: 5
Color: reddish-brown to grey
Luster: metallic to earthy

Identified June 28, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5 Mohs; Color: reddish-brown to grey; Luster: metallic to earthy; Crystal Structure: Trigonal (often found in botryoidal or concretionary forms); Specific Gravity: 5.26.

Formation & geological history

Formed through the precipitation of iron-rich fluids passing through porous sedimentary rock (like sandstone). These concretions grow over thousands to millions of years around a central nucleus.

Uses & applications

Primarily used as an ore of iron. Also used in pigments, jewelry (beads), and as a popular specimen for educational or metaphysical collections.

Geological facts

These are often nicknamed Moqui Marbles, Martian Blueberries, or Shaman Stones. Similar hematite nodules were discovered on Mars by the Opportunity rover, suggesting liquid water was once present.

Field identification & locations

Identify by their high weight relative to size (high density), reddish-brown streak, and often perfectly spherical or pebble-like shapes. Found in arid sedimentary basins like the Navajo Sandstone in Utah.