File:Gold-Crystalline placer gold (skeletal octahedral crystal; hopper octahedral crystal) (5.5 mm across) from the Santa Elena Placer Gold District of Venezuela. (8284270519).jpg
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Gold nuggets found in rivers & streams (= placer gold) usually have irregular, somewhat rounded shapes. It’s rare to find placer gold having a crystalline structure. Geologic context: placer gold in modern alluvial deposit; gold is derived from weathering of conglomeratic paleoplacers in the Uairén Formation, Roraima Supergroup, upper Paleoproterozoic, ~1.7-1.8 billion years. Locality: unrecorded locality in the Santa Elena Placer Gold District, near Santa Elena de Uairén, Grand Savannah River region (La Gran Sabana), southeastern Bolivar State, southwestern Guyana Highlands, southeastern Venezuela. Here’s a nice gold crystal from Venezuela’s Santa Elena Placer Gold District. This is the top of the specimen, showing the upper half of an octahedral crystal (a square pyramid). Notice that each of the four faces of the pyramid are embayed. Such features are not uncommon in natural crystals. The terms hopper octahedron or skeletal octahedron would be applicable here. A few grains of sediment are stuck at the bottom of a couple of these cavities (e.g., just visible in the bottom cavity of the photo). |
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| Author | James St. John |
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This image, originally posted to Flickr, was reviewed on 2 February 2014 by the administrator or reviewer File Upload Bot (Magnus Manske), who confirmed that it was available on Flickr under the stated license on that date. |
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| current | 20:23, 2 February 2014 | | 960 × 720 (67 KB) | File Upload Bot (Magnus Manske) (talk | contribs) | Transferred from Flickr by User:PDTillman |
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