NORTHWESTERN OHIO : CALCITE , DOLOMITE AND FLUORITE 1
Calcite is by far the most abundant mineral in the Devonian rocks at Pugh Quarry. The large crystals, from 5 mm to 10-15 cm long, are predominantly brown with wide variations in hue and intensity. The small crystals, smaller than 5 mm, range from colorless to gray-yellow to pale yellow. Both large and small crystals consist almost entirely of scalenohedral forms (dog-tooth spar habit). The most common and most easily recognized type of twinning in the large crystals is on the (0001) plane. Both dolomite and fluorite are minor minerals at Pugh Quarry, although fiuorite is found in all parts of the Quarry. Dolomite crystals occur as secondary encrusting material and are most common in vugs. OHIO J. SCI. 79(1): 24, 1979 In this third paper on the mineralogy of Pugh Quarry, calcite, dolomite and fluorite are described. The quarry is located in the SW3^, SW^, Sec. 6, T.4N, R.9E in Milton Township, Wood Co., Ohio. Its sulfide mineralization, including marcasite, pyrite, and sphalerite has been previously described (Parr and Change 1977, 1978).
Descriptive Mineralogy of Pugh Quarry, Northwestern Ohio: Marcasite and Pyrite
Minerals from solution cavities and associated collapse breccias in the Middle Devonian dolostone at Pugh Quarry, Wood County, Ohio were collected and identified. Two types of marcasite were recognized: banded encrustations and euhedral crystals. The banded marcasite is widespread in the mineral zone, especially in the northeastern section of the Quarry, and showed 3 distinct habits: subhedral, globular, and columnar. On freshly exposed surfaces, the colors were greenish gray or a mixture of pale yellow and gray. A characteristic of the banded marcasite is the presence of extensive intergrowth twinning. The euhedral marcasite was found in rocks in all parts of the Quarry, both inside and. outside the mineral zone. On freshly broken surfaces, the euhedral crystals were gray-white with a greenish cast. Prismatic and tabular habits were observed. Many of the crystals showed hopper development. Pyrite is not a common mineral in Pugh Quarry. Generally, crystals were small, less than 1 mm in size, greenish brown to yellowish brown in color, and highly lustrous. OHIO J. SCI. 77(5): 213, 1977 Museums and private mineral collections throughout the U.S. and other countries display crystal specimens of carbonate, sulfate, and sulfide minerals from quarries in the Paleozoic carbonate rocks in the mid-western United States. Occurrence of these minerals has been previously reported (Kraus 1905; Ford and Pogue 1909; Morrison 1935; Howard 1951), but little work has been done on their descriptive mineralogy. It is the purpose of this study to provide a detailed investigation of the mineral assemblages in the carbonate rocks at Pugh Quarry, which is located in the SW]^, SWM, Sec. 6, T.4N., R.9E. in Milton Township, Wood Co., Ohio. In this report, marcasite and pyrite are described. Methods used for investigation in this study included megascopic identification, microscopic examination of thin sections and polished sections, reflecting goniometric measurement, and x-ray powder diffraction studies. Manuscript received June 24, 1976 and in final revised form May 3, 1977 (#76-54). Present Address: Department of Geology, Wisconsin State University, Superior, WisMINERAL OCCURRENCE The stratigraphy at Pugh Quarry is shown in figure 1. Wisconsin age till and lacustrian sands form the overburden at Pugh Quarry. Glacial grooves and striations were exposed on the bedrock around the quarry rim where the overburden had been stripped back. Stylolites occurred in the strata exposed at Pugh Quarry. Petroliferous black shale seams approximately 6 mm thick separated the rocks above and below stylolites, and brecciation was common. Marcasite, pyrite, and 6 other minerals occurred in rocks at Pugh Quarry (table 1). The minerals were generally restricted to a zone (referred to hereafter as the mineral zone) consisting of nearly continuous bands of cavities about 9 cm thick located in the upper 18 to 24 cm of the Anderson Formation of the Detroit River Group (see fig. 1). Brecciation in this mineral zone locally resembled collapse phenomena associated with areas of cavern development. It was similar to the brecciation described by Jackson and Beales (1967) in ore zones of the Oklahome-Kansas-Missouri Tri-State Mining District. The breccias in both cases
The Inca Occupation of the South Coast of Peru
like the others, however; it forks into several nearly parallel ravines of which the largest are Huayuri, Rio Grande-Palpa, Ingenio (called Collao in ancient times), Nasca proper (the ancient Caxamarca), Taruga, and Poroma. Due to peculiarities of the local topography, the irrigated areas in Ica and the ravines of Nasca are located inland, at the foot of the mountains, rather than at the mouths of the rivers as is more usual in Peruvian coastal valleys. No sharp natural or cultural boundary separates the valley of Chincha from the valleys of Cafiete (ancient Huarco and Runahuana), Asia, and Mala, the next valleys going up the coast to the northwest. At the other end of the area we are considering, however, there is a sharp break; beyond Yauca the Andean foothills reach out to the sea, natural conditions are quite different, and there are important differences in the archaeological picture as well. The historical sources which mention the south coast are not particularly helpful, except in so far as they provide us with a few dates. To begin with, no chronicler gives an explicit account of the political organization of the south coast at the time it came into contact with the Incas. It can, perhaps, be inferred from Cabello Balboa's statements about common policy toward the Inca invaders that there was some sort of political connection between the valleys of Mala, Cafiete, and Chincha, but the connection need have been no more than a temporary military alliance. Cabello makes no mention at all of Pisco. The valleys of Ica, Nasca, and 125