"The occurrence of sulfide minerals and their textural relationships to the silicate and oxide minerals in the Benson Mines, New York, iron deposit were investigated by ore microscopic and petrographic means. The Benson deposit is one in which the dominant iron oxides, magnetite and hematite, occur in a quartz-feldspar gneiss which was subjected to hornblende granulite subfacies metamorphism. Two hundred ore and country rock specimens were systematically collected from all parts of the open pit mine. Polished sections and thin sections were prepared from nearly all of the collected specimens. The oxide ore exhibits a granular texture in which isolated magnetite and hematite grains approach an ovate shape. The oxides show no replacement of the silicates, and some textures appear to indicate either that part of the oxides were present during metamorphism or that part of the silicates formed during and after oxide deposition. Such textures include poikiloblastic oxide ore inclusions in garnet and sillimanite, and complete rims of garnet and sillimanite around oxide ore grains. The most common sulfides are pyrite, pyrrhotite, and chalcopyrite, but minor quantities of bornite and covellite are locally present. Part of the sulfide grains exhibit textures exactly like those of the oxides, but others show clearly cross cutting textures. such textures include veinlets across oxide, silicate, and earlier sulfide grains, ragged replacements along oxide silicate and earlier sulfide grain boundaries and replacements along silicate cleavages. Polycrystalline aggregates of marcasite have, in turn, partially replaced both the earlier ovate pyrite and the later transgressive pyrite"--Abstract, page ii-iii.
Hagni, Richard D.
Legsdin, Adolph, 1899-1969
Geosciences and Geological and Petroleum Engineering
M.S. in Geology
University of Missouri--Rolla
viii, 70 pages, maps
New York (State)
© 1968 Pedro Hugo Tumialán, All rights reserved.
Thesis - Open Access
Library of Congress Subject Headings
Geology -- New York (State)
Petrology -- New York (State)
Sulfide minerals -- Analysis
Print OCLC #
Electronic OCLC #
Link to Catalog Recordhttp://laurel.lso.missouri.edu/record=b1067717~S5
Tumialán de la Cruz, Pedro Hugo, "Sulfide mineralogy and fabrics of the iron ores at Benson Mines, New York" (1968). Masters Theses. 5250.