Photo Gallery: Fantastic Moqui Marbles

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Game of stones

moqui marbles

(Image credit: Marjorie Chan, University of Utah)

Unusual find

Iron concretions, Zion National Park

(Image credit: NPS)

The unusual geologic formations are concretions — sandstone balls cemented by a hard shell of iron oxide minerals.

Amazing view

Zion National Park

(Image credit: National Park Service)

Millions of years in the past, a mixture of water and natural gas flowed through the Navajo Sandstone, bleaching the rocks from red to creamy white. The stolen iron became the moqui marbles.

Checkerboard Mesa

Checkerboard Mesa, Zion National Park

(Image credit: NPS)

At Checkerboard Mesa in Zion National Park, the Navajo Sandstone is creamy white.

Red rocks

Navajo Sandston arch, Zion National Park

(Image credit: National Park Service)

The lower levels of Navajo Sandstone at Zion are stunning red, orange and peach colors.

Field of dreams

moqui marbles

(Image credit: Marjorie Chan, University of Utah)

The concretions collect in topographic lows.

Oddballs

moqui marbles

(Image credit: National Park Service)

Moqui marbles come in many shapes and sizes.

Hard stuff

Navajo sandstone

(Image credit: National Park Service)

Resistant iron minerals erode more slowly than the softer sandstone.

Lumps and bumps

moqui marbles

(Image credit: Marjorie Chan, University of Utah)

The spheres grew layer by layer, making contact with others nearby until many spheres became one large ball.

Fine polish

moqui marbles

(Image credit: Marjorie Chan, University of Utah)

Wind-blown sand polishes the outer shell of hematite or goethite.

Bleached clean

moqui marbles

(Image credit: Marjorie Chan, University of Utah)

Moqui marbles emerge from cream-colored Navajo sandstone.

Becky Oskin
Becky Oskin
Contributing Writer
Becky Oskin covers Earth science, climate change and space, as well as general science topics. Becky was a science reporter at Live Science and The Pasadena Star-News; she has freelanced for New Scientist and the American Institute of Physics. She earned a master's degree in geology from Caltech, a bachelor's degree from Washington State University, and a graduate certificate in science writing from the University of California, Santa Cruz.