mineral

Hematite Nodules (Moqui Marbles)

Ferric Oxide (Fe2O3)

Hardness: 5-6.5 (Mohs scale); Color: Dark brown, black, to metallic grey; Luster: Metallic to earthy; Crystal Structure: Trigonal (often found in botryoidal or concretionary forms); Specific Gravity: 5.26

Hardness: 5-6
Color: Dark brown, black, to metallic grey
Luster: Metallic to earthy

Identified June 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed by the precipitation of iron oxide from mineral-rich groundwater flowing through porous sandstone. These nodules often grow around a nucleus like a shell or sand grain over millions of years.

Uses & applications

Primary ore for iron production. Also used as jewelry, in pigments (red ochre), as a polishing agent (jeweler's rouge), and in alternative healing practices.

Geological facts

Hematite is famous for its 'blood-red' streak when rubbed against an unglazed porcelain plate. On Mars, spherical hematite concretions are nicknamed 'blueberries' and provided evidence of past water.

Field identification & locations

Identify by its high density (feels heavy for its size) and its reddish-brown streak. Commonly found in desert environments like the Southwestern United States, particularly in the Navajo Sandstone.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral