02459cam a2200361 i 4500 5386107 20071022125843.0 750609s1975 ilua b 000 0 eng 74028959 (OCoLC)ocm01501965 DLC DLC BTCTA UIU n-usc-- QE1 .F4 vol. 33, no. 7 QE471.15.C58 550/.8 s 552/.5 UIUU Woodland, Bertram G. Pyritic cone-in-cone concretions / Bertram G. Woodland --. Cone-in-cone concretions Chicago : Field Museum of Natural History, 1975. p. 125-139 : 15 ill. ; 24 cm. Fieldiana. Geology ; v. 33, no. 7 Field Museum of Natural History. Publication 1200 "February 10, 1975." "This volume is dedicated to Dr. Rainer Zangerl." Includes bibliographical references (p. 138-139). A number of pyritic cone-in-cone concretions from Middle Pennsylvanian black shales of Indiana and Illinois are described. These are the only occurrences of typical cone-in-cone structure composed of pyrite that are known to the author, other than those described from Cambrian and Ordovician shales of the Oslo region, Norway. The Indiana concretions have a core of earthy, phosphatic material, probably coprolitic; the Illinois specimen is an isolated cone. Both occurrences have the typical fabric and structure of the usual calcitic (dolomitic) cone-in-cone. The latter is diagenetic in origin and has formed as a direct consequence of fibrous growth in semi-consolidated sediments. Because of this, the striking similarity of structure between the pyritic and carbonate types, and the contrasts between the crystal habits of calcite and pyrite, the pyritic cone-in-cone is interpreted as a pyrite replacement of original carbonate cone-in-cone concretions. Fieldiana series has been published as Geological Series by Field Columbian Museum (1895-1909) and Field Museum of Natural History (1909-1943), and as Fieldiana: Geology by Chicago Natural History Museum (1945-1966) and Field Museum of Natural History (1966-). Concretions Middle West. Pyrites Middle West. Geology, Stratigraphic Pennsylvanian. Publication (Field Museum of Natural History) ; 1200. Baker and Taylor BTCP 74028959 //r892 C0 UIU