Geology topics

William R. Greenwood

Publications and source records attributed to William R. Greenwood.

3 recordsLinked to original sources

USGS1990

Mineral resources of the Elkhorn Wilderness Study Area, Broadwater and Jefferson Counties, Montana

The Elkhorn Wilderness Study Area in west-central Montana has a moderate to high potential for resources of porphyry-type copper and molybdenum in the western part of the area, and a moderate to high potential for resources of gold, silver, lead, and zinc in replacement and vein deposits in the eastern part of the area. No evidence of potential oil, gas, and geothermal resources was identified in this study.

Montana↗

USGS1978

Comparison of the Wilfley concentration table and hand panning for concentration of heavy minerals prior to geochemical analysis

Chemical analysis of heavy—mineral concentrates of stream sediments is a common geochemical exploration technique used by the U.S. Geological Survey. Generally these concentrates are prepared by hand panning at streamside or in a washtub and then further concentrated using heavy—liquid (bromoform) techniques in a laboratory. Concentration using heavy liquids is slow, tedious, and expensive for large surveys such as mineral evaluation of wilderness areas. In addition the cost of bromoform is expected to increase greatly because most if not all chemical companies in the United States have ceased production of the compound due to problems in meeting the safety standards of the U.S. Environmental Protection Agency (E.P.A.). Preliminary studies by the E.P.A. suggest a severe health hazard may be incurred by inhaling vapors of or contacting the skin with chemicals like bromoform. Heavy—liquid concentration of thousands of heavy— mineral samples carries an unavoidable risk of exposure to bromoform. The risk, expense, and time required by routine heavy—liquid concentration of heavy minerals should be eliminated by finding other methods to satisfactorily concentrate minerals whenever it is possible. Heavy—mineral concentrates can be used in several ways in geochemical exploration and each way has certain standards for the nature and quality of the mineral concentration required. The nature of the concentration refers to whether the heavy minerals are analyzed in bulk or whether they are split into magnetic fractions using a hand magnet and possibly a Frantz Isodynamic Magnetic Separator.

Open-File Report↗

USGS1975

Mineral deposits in western Saudi Arabia; a preliminary report

Mineral deposits in Saudi Arabia include a variety of deposits which were formed in many geologic environments. These include magmatic and late magmatic deposits in igneous masses, contact metamorphic deposits along the margins of igneous bodies, and stratiform sulfide deposits and veins. Notable deposits of sedimentary origin include deposits of iron oxides and phosphate. Strata-bound massive sulfide deposits containing copper, zinc, and nickel sulfides associated with pyrite and pyrrhotite in complexly deformed volcanic rocks in Saudi Arabia have been the subject of controversy. They are considered by some geologists to be of syngenetic or volcanogenic origin, and by others to be epigenetic. The principal mineral deposits in western Saudi Arabia are localized in mineral belts within tectonic zones that trend northerly, northeasterly, and northwesterly. These belts contain the exploration target areas most promising for future exploration. Noteworthy among these are: 1) the northerly-trending Bidah copper-zinc belt; 2) the Sayid copper-zinc zone; 3) the northwest-trending Nuqrah copper zinc-silver belt; and 4) the north-northwesterly-trending Al Amar belt. Gold and silver deposits are mainly localized in north-trending structural features of the Hijaz geotectonic cycle and northwest Najd trends. Saudi Arabian metal deposits known thus far contain reserves in the 2 billion dollar range. Further exploration should result in discoveries that could significantly increase this amount; Saudi Arabia may well have workable metallic and nonmetallic mineral resources for industrial developments in many parts of the Kingdom. In order to effectively carry on a search for new mineral deposits, the belts should be mapped in detail, with emphasis on the delineation of stratigraphic and structural features that control metallization. In addition, geochemical and geophysical studies should be made of promising areas to outline exploration targets. These targets could then be systematically explored.

Open-File Report↗