File:Thunder Egg Agate (Priday Blue Bed, John Day Formation, Miocene; near Madras, Oregon, USA) 5.jpg
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Summary
| Description |
English: Agate ("Thunder Egg") from the Tertiary of Oregon, USA. (9.2 centimeters across at its widest)
"Agate" is a rockhound/collector term for cavities in rocks (usually sedimentary rocks such as limestone or igneous rocks such as basalt) that have been partially or completely filled with irregularly concentric layers of microcrystalline, fibrous quartz (chalcedony - SiO2). Agate is quartz. "Thunder eggs" are agate-filled masses that fill former cavities in volcanic rocks (see Colburn, 2004 for more info.). Stratigraphy: unrecorded (but probably the Priday Blue Bed, John Day Formation, Miocene) Locality: unrecorded site in Oregon, USA (but probably Richardson Ranch / Richardson's Rock Ranch, northeast of the town of Madras, Jefferson County, north-central Oregon) Reference cited: Colburn (2004) - The Formation of Thundereggs (Lithophysae). 493 pp. |
| Date | |
| Source | https://www.flickr.com/photos/47445767@N05/51579315935/ |
| Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/51579315935. It was reviewed on 12 October 2021 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 18:01, 12 October 2021 | | 4,406 × 3,591 (15.73 MB) | Ser Amantio di Nicolao | Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/51579315935/ with UploadWizard |
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