![]() NPS photo/Sarah Stio
The range of colors of the Navajo Sandstone –red, brown, pink, salmon, gold, and even white—results from varying amounts and forms of iron oxide within the rock, and in the case of the white upper portion of the Navajo, the overall lack of iron.
The processes behind the color variation are complex and took place in multiple phases over long periods of time. To start, the Navajo is made of grains of light-colored quartz sand, similar to those found in many modern dune or beach environments. Soon after being deposited in dunes, the sand grains were coated with a thin layer of reddish-brown iron oxide (the mineral hematite; a.k.a. rust). This was due to the chemical breakdown (oxidation) of very small amounts of iron-containing minerals within the sand, and made the earlier Navajo Sandstone a pinkish-red color overall.
![]() NPS photo/Adrienne Fitzgerald ![]() NPS photo/Adrienne Fitzgerald These dark, iron-enriched concretions and layers are more resistant to erosion than the regular Navajo Sandstone, often leaving them standing out in positive relief against the softer sandstone.
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Last updated: June 13, 2015