Manganese nodule.
Hydrogenous sedimentary rock.
Manganese nodules are a small concretion consisting of manganese and iron oxides, occurring in large numbers in ocean-floor sediment.
The sample shown here is a larger chunk of manganese ore, possibly from an ancient "black smoker" (hot hydrothermal fluid metal deposit) associated with vents on the seafloor. This sample came from a river terrace gravel deposit along the Mojave River east of Barstow, California. Whether it came from an ancient seafloor deposit is uncertain. |
| https://gotbooks.miracosta.edu/rocks/sedimentary/22.html |
2/2/2021 |
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