Silicified favositid coral (Middle Paleozoic; Salt Creek gravel bar clast, Haynes, Ohio, USA) 3 : 無料・フリー素材/写真
Silicified favositid coral (Middle Paleozoic; Salt Creek gravel bar clast, Haynes, Ohio, USA) 3 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Silicified fossil coral from the Middle Paleozoic. (~5.5 cm across at its widest)Replacement is a fossil preservation style involving the crystal structure and the mineral of an organism's hard parts being changed.The most common replacement mineral is quartz (silica) (SiO2) - fossils that have been replaced by quartz are said to be silicified (silicification). Many silicified fossils have rounded to pustulose structures covering their surfaces. These are called beekite rings, but they're composed of ordinary quartz.Other common replacment materials include the mineral pyrite (FeS2 - iron sulfide) and calcium phosphate. These replacement styles are called pyritization and phosphatization.Numerous other minerals have been found replacing minerals - many of them are quite rare. Reported fossil replacement minerals include: anglesite, apatite, barite, calamine, calcite, cassiterite, celestite, cerargyrite, cerussite, chalcocite, cinnabar, copper, dolomite, fluorite, galena, garnet, glauconite, gumbelite, gypsum, hematite, kaolinite, limonite, magnesite, malachite, marcasite, margarite, opal, pyrite, romanechite/psilomelane, siderite, silica/quartz, silver, smithsonite, specular hematite, sphalerite, sulfur, uranium minerals, and vivianite. (List mostly from info. in Hartzell, 1906 and Klein & Hurlbut, 1985)This fossil is a silicified tabulate coral. Tabulates are an extinct group of colonial corals - they only occur in Paleozoic rocks. The traditional four groups of tabulates are favositids, syringoporids, halysitids, and auloporids Tabulates were essentially colonies of sea anemones that made calcareous, hard-part skeletons.This specimen is a silicified favositid coral. They made honeycomb-like skeletons. Corallites are closely-packed and frequently have pentagonal to hexagonal outlines. Silicification has resulted in numerous geodized cavities in this fossil. Small quartz crystals line each void.Classification: Animalia, Cnidaria, Anthozoa, Tabulata, FavositidaeProvenance: clast atop a modern fluvial gravel bar; derived from a Middle Paleozoic unitLocality: Salt Creek, a little west of Route 56 & north of Election Road, Haynes, southwestern Hocking County, southern Ohio, USA |
| 撮影日 | 2017-12-11 18:07:11 |
| 撮影者 | James St. John |
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