sedimentary

Moqui Marble

Iron Oxide Concretion (Limonite/Hematite over Sandstone)

AI-generated identification · may be incorrect

Hardness: 5.0 - 5.5 on Mohs scale (outer shell); Color: Brown to dark black exterior with tan interior; Luster: Dull, earthy; Crystal structure: Amorphous; Cleavage: None; Specific gravity: 3.5 - 4.5.

Hardness: 5
Color: Brown to dark black exterior with tan interior
Luster: Dull, earthy

Identified March 30, 2026More sedimentary →

Explore Moqui Marble in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed roughly 25 million to 300,000 years ago via groundwater precipitation. They form when iron-rich minerals precipitate in the pore spaces between sand grains in host sandstone (predominantly the Navajo Sandstone formation).

Uses & applications

Predominantly used as collectible geological specimens and in metaphysical practices as 'balancing stones.' Also used as a curriculum aid for teaching about groundwater chemistry and Martian geology.

Geological facts

They are terrestrial analogues to the 'Blueberries' found on Mars by the Opportunity rover. The name 'Moqui' comes from the Hopi tribe (formerly referred to as the Moqui people), whose folklore suggests ancestors played games with the marbles.

Field identification & locations

Identify in the field by their spherical or blueberry-like shape emerging from sandstone cliffs or scattered on desert floors. Primarily found in the Grand Staircase-Escalante National Monument in southern Utah. Note: Collecting is strictly illegal within National Parks/Monuments.