The Rocks and Minerals of Occoneechee Mountain -

Goethite

Goethite (FeO OH) is a common iron hydroxide mineral. It typically forms from the oxidation of iron-bearing minerals (example pyrite). Goethite can contain absorbed water molecules causing a rainbow-like coloration as in the photograph.

Goethite (the brown mineral) forms a precipitate on the quartzite-like rock in the photograph.

goethite
Enlarged portion of above photograph showing rainbow-like coloration caused by the absorbed water molecules in the goethite. goethite

Boulders similar to the photograph are common in the abandoned quarry. The reddish-brown zones may have been pyrite masses that have been altered to goethite and other iron oxides. The white areas of the boulder are composed of the mineral pyrophyllite and sericite.

goethite

Please remember that rock and mineral collecting is STRICTLY PROHIBITTED in Eno River State Park!

 

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Want to learn more about the geology of the Eno River area?

You may be interested in A Geologic Adventure Along the Eno River - A richly illustrated publication from the North Carolina Geological Survey.