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Analyses of Coals in the United States with Descriptions of Mine and Field Samples Collected between July 1, 1904 and June 30, 1910 Part 2. Descriptions of Samples
From Introduction: "This volume contains the descriptions of the samples whose analyses are published in the preceding volume, Part I of this bulletin. The descriptions have been compiled from the notebooks of the persons who collected the samples, have been condensed from accounts given in published reports of the United States Geological Survey, or have furnished by the collection themselves. Inasmuch as the descriptions represent the work of many persons during a period of six years, and inasmuch as they were recorded under widely differing conditions, they necessarily vary in fullness detail."
Date:
1913
Creator:
Lord, N. W.
System:
The UNT Digital Library
Thorium and rare earth minerals in the Powderhorn district, Gunnison County, Colorado
"Thorium deposits were discovered in the Powderhorn district in 1949. This district has long been known for its occurrences of alkalic igneous rocks, of which the best known is the Iron Hill complex (Larsen, 1942). Some of these alkalic rocks contain titanium, barium, strontium, rare earths, thorium, and niobium in greater percentages than those of most igneous rocks. A study of the thorium deposits was undertaken to obtain more information on the geologic relation of minor elements, particularly rare earths, and thorium, to alkalic igneous rocks, and to evaluate the economic significance of the Thorium deposits."
Date:
February 1954
Creator:
Olson, J. C. & Wallace, S. R.
System:
The UNT Digital Library
Shorter Contributions to General Geology, 1941-42
Preface: The author of this paper gives a thorough description of a complex of very unusual igneous rocks and associated hydrothermal deposits.
Date:
1942
Creator:
Geological Survey (U.S.)
System:
The UNT Digital Library