File:Furcaster paleozoicus fossil brittle star (Kaub Formation, Hunsrück Slate Group, Lower Devonian; Budenbach area, western Germany) 4 (15302668235).jpg
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Summary
DescriptionFurcaster paleozoicus fossil brittle star (Kaub Formation, Hunsrück Slate Group, Lower Devonian; Budenbach area, western Germany) 4 (15302668235).jpg |
Furcaster paleozoicus Stürtz, 1886 - pyritized fossil brittle star from the Devonian of Germany. (field of view ~4.4 centimeters across) The Devonian-aged Hunsrück Slate Lagerstätte is one of the most famous soft-bodied fossil deposits. Hunsrück fossils have been pyritized (replaced with pyrite/“fool’s gold” - FeS2). They occur in a black slate matrix - the result is beautiful brassy gold colored fossils on a dark background. A diverse biota has been described, including trilobites with preserved legs & gills, crinoids, starfish & brittle stars, “worms”, molluscs, corals, conulariids, sponges, cnidarians, land plants, “algae”, fish, plus various unusual arthropods & echinoderms. The Hunsrück Slate Lagerstätte occurs in the Kaub Formation (Hunsrück Slate Group, lower Emsian Stage, upper Lower Devonian) in the Budenbach area of western Germany. Preparation of Hunsrück fossils is notoriously difficult, and many of the pyritized fossils crumble to dust from pyrite disease over many years. Relatively recently, a “secret” air abrasion method has been successfully used to prepare Hunsrück fossils, using an abrasive grit composed of metallic iron powder mixed with potato starch. Shown here is a pyritized, complete fossil brittle star (ophiuroid) from the Hunsrück. All five arms are bent in the same direction, indicating current direction before final burial. This is a Furcaster paleozoicus brittle star, a species first described by Bernhard Stürtz in 1886. Classification: Animalia, Echinodermata, Asterozoa, Ophiuroidea, Oegophiurida, Zeugophiurina, Furcasteridae 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 The most common replacement mineral is quartz (silica) (SiO2) - fossils that have been replaced by quartz are said to be silicified (silicification).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) See info. at: <a href="https://wiki.riteme.site/wiki/Hunsrück_Slate" rel="noreferrer nofollow">wiki.riteme.site/wiki/Hunsrück_Slate</a> |
Date | |
Source | Furcaster paleozoicus fossil brittle star (Kaub Formation, Hunsrück Slate Group, Lower Devonian; Budenbach area, western Germany) 4 |
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@N05/15302668235 (archive). It was reviewed on 7 December 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
7 December 2019
Items portrayed in this file
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5 April 2006
0.003125 second
4.5
105 millimetre
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 18:55, 7 December 2019 | 3,008 × 2,000 (5.21 MB) | Ser Amantio di Nicolao | Transferred from Flickr via #flickr2commons |
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Exposure time | 1/320 sec (0.003125) |
F-number | f/4.5 |
Date and time of data generation | 23:32, 5 April 2006 |
Lens focal length | 105 mm |
Orientation | Normal |
Horizontal resolution | 300 dpi |
Vertical resolution | 300 dpi |
Software used | Adobe Photoshop CS2 Macintosh |
File change date and time | 19:53, 20 September 2014 |
Y and C positioning | Co-sited |
Exposure Program | Normal program |
Exif version | 2.21 |
Date and time of digitizing | 23:32, 5 April 2006 |
Meaning of each component |
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Maximum land aperture | 3.7 APEX (f/3.61) |
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DateTime subseconds | 20 |
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Scene type | A directly photographed image |
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Date metadata was last modified | 15:53, 20 September 2014 |