Moqui Marbles are naturally occurring iron oxide concretions found in the Navajo Sandstone formation. They typically appear as spherical to disc-shaped brown balls with a hard outer shell of hematite and a soft interior of sandstone, formed through ground water mineral precipitation.
Is this moqui marbles?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch moqui marbles with a known reference. Moqui Marbles sits at Mohs 5.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: reddish-brown.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: brown, reddish-brown, black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: spherical concretions.
Often found alongside moqui marbles
Minerals reported to co-occur with moqui marbles. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₂O₃
- Mohs hardness
- 5.5-6.5
- Density
- 4.5-5.2 g/cm³
- Colors
- Streak
- Reddish-brown
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Spherical concretions
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Metaphysical
- Host rock
- sedimentary sandstone
Where rockhounds find moqui marbles
Classic worldwide localities
- Navajo Sandstone, Utah, USA
- Grand Staircase-Escalante National Monument, USA
Field-hunting tip
Where it forms: sedimentary sandstone. If you start seeing quartz, sandstone in float, you are in the right ground. Typical habit: spherical concretions. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify moqui marbles?+
Where is moqui marbles found?+
What minerals are found with moqui marbles?+
What kind of rock does moqui marbles form in?+
What is moqui marbles used for?+
Find moqui marbles on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
