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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 19 recordsLinked to original sources
USGS1990

Fluorian garnets from the host rocks of the Skaergaard intrusion: implications for metamorphic fluid composition

Zoned, silica-deficient, calcic garnets containing up to 5 mol% F substitution for O formed during contact metamorphism of basalts by the Skaergaard intrusion in East Greenland. Fluorian calcic garnets occur as a retrograde alteration of prograde wollastonite and clinopyroxene that fills vesicles and vugs in lavas 30-70 m from the intrusion. The F content of garnet is extremely sensitive to minor changes in fluid composition. The calculations show that a decrease in pH or an increase in log aF- of 0.3 at constant pressure and temperature will decrease the F concentration in garnet from 5 to 0 mol%. The results of this study show that fluorian hydrous grandites provide a mineralogical record of the activities of F species in coexisting metamorphic and hydrothermal fluids. -from Authors

American Mineralogist↗
USGS1978

Mineralogical analyses of drill core samples from Midlands Gas Corporation wells, Federal 0370 No. 1 and Federal 2962 No. 1, Phillips County, Montana

This report records the mineralogy of core samples from two wells in Phillips County, Montana. These wells are located in the Bowdoin gas field in north-central Montana. The gas is produced from low-permeability reservoirs at shallow depths (less than 610 m) over an area of 1554 km 2 . This information is being released to aid in improving recovery technology and well log interpretation. We acknowledge the financial support of the Department of Energy Tight Gas Sands program.

Montana↗
USGS1984

Characterization of the oil shale of the New Albany Shale in Indiana

In the 1920's chemical and mineralogic characterization of the New Albany Shale (Mississippian-Devonian) in Indiana showed the dark shale to be rich in organic material and have commercial possibilities. Projects in the 1960's resulted in disparaging descriptions of exiguous fossil record, monotonous mineralogy, and intractable chemistry. Since 1978 expanded efforts have yielded much new information but new problems as well. Although organic carbon and total sulfur show positive correlation, two nearly exclusive populations exist. Material high in organic carbon is more depleted in C13 than material with less organic carbon. A bed usually at the top of the unit hosts anomalous accumulations of heavy metals and contains concentrations in similar ratios to those of sea water except for Mo and Pb and shows very negative ??S34. Heat content as Btu/lb, organic carbon (total less inorganic), and Fischer assay oil-yields generally correlate, but one is not an accurate predictor of the others.

Conference Paper↗
USGS2009

Weathering of the New Albany Shale, Kentucky, USA: I. Weathering zones defined by mineralogy and major-element composition

Comprehensive understanding of chemical and mineralogical changes induced by weathering is valuable information when considering the supply of nutrients and toxic elements from rocks. Here minerals that release and fix major elements during progressive weathering of a bed of Devonian New Albany Shale in eastern Kentucky are documented. Samples were collected from unweathered core (parent shale) and across an outcrop excavated into a hillside 40 year prior to sampling. Quantitative X-ray diffraction mineralogical data record progressive shale alteration across the outcrop. Mineral compositional changes reflect subtle alteration processes such as incongruent dissolution and cation exchange. Altered primary minerals include K-feldspars, plagioclase, calcite, pyrite, and chlorite. Secondary minerals include jarosite, gypsum, goethite, amorphous Fe(III) oxides and Fe(II)-Al sulfate salt (efflorescence). The mineralogy in weathered shale defines four weathered intervals on the outcrop-Zones A-C and soil. Alteration of the weakly weathered shale (Zone A) is attributed to the 40-a exposure of the shale. In this zone, pyrite oxidization produces acid that dissolves calcite and attacks chlorite, forming gypsum, jarosite, and minor efflorescent salt. The pre-excavation, active weathering front (Zone B) is where complete pyrite oxidation and alteration of feldspar and organic matter result in increased permeability. Acidic weathering solutions seep through the permeable shale and evaporate on the surface forming abundant efflorescent salt, jarosite and minor goethite. Intensely weathered shale (Zone C) is depleted in feldspars, chlorite, gypsum, jarosite and efflorescent salts, but has retained much of its primary quartz, illite and illite-smectite. Goethite and amorphous FE(III) oxides increase due to hydrolysis of jarosite. Enhanced permeability in this zone is due to a 14% loss of the original mass in parent shale. Denudation rates suggest that characteristics of Zone C were acquired over 1 Ma. Compositional differences between soil and Zone C are largely attributed to illuvial processes, formation of additional Fe(III) oxides and incorporation of modern organic matter.

Applied Geochemistry↗
USGS1983

Taeniolite, an uncommon lithium-mica from Coyote Peak, Humboldt County, California.

Taeniolite has been found in a late pegmatitic clot in a mafic alkalic diatreme at Coyote Peak; associated species are natrolite, pectolite, aegirine, barytolamprophyllite, rasvumite and sphalerite. The taeniolite is green-brown with sp. gr. (meas.) 2.85(1) and H. 31/2. Optically it is biaxial (-) with alpha 1.541(2), beta = gamma 1.570(2), 2V approx 0o and moderate pleochroism with gamma = beta reddish-brown, alpha pale greenish brown. Single-crystal precession photographs show it to be of the 1M type, with a 5.254(2), b 9.110(4), c 10.187(2) A, beta 99.85(4)o and V = 480.4(1) A3. Combined microprobe and ion probe analyses gave SiO2 53.5, Al2O3 3.00, TiO2 1.06, FeO 3.35, MnO 0.21, MgO 18.3, Li2O 2.4, K2O 11.3, Na2O 0.27, F 6.3 = 99.69; SrO and BaO are both <0.04 wt.%; B, Be, Ca and Cl were not detected. Assuming (F + OH) = 2 and assigning 1.30 wt.% H2O gives 409(K1.01Na0.04)(Al0.01Ti0.06Fe2+0.20Mn0.01Mg1.92Li0.68)(Si3.76Al0.24)O10- (F1.40OH0.60).-G.W.R.

Mineralogical Record↗
USGS1983

Cuprian fraipontite and sauconite from the Defiance-Silver Bill mines, Gleeson, Arizona.

XRD studies have shown the fine-grained, light blue-green mineral previously identified as turquoise or chrysocolla to be the rare species fraipontite + or - admixed sauconite. Composite microprobe and XRF analyses gave SiO2 24.8, Al2O3 17.3, CaO 0.34, CuO 5.2, ZnO 40.95, H2O (ign. loss, 900oC) 12.8, = 101.39, yielding the formula (Zn1.84Al0.77Cu0.24box 0.13- Ca0.02)3.00(Si1.51Al0.49)2.00O5(OH)4. Semiquantitative emission spectrographic analysis showed Fe 0.007, Mg 0.01, Ca 0.07, Si 10, Al major, Na 0.015, Zn major, Cu 5%; Mn 15, B 150, Be 7, Ni 50, Pb 15, Sc 15, Ga 70 and Ag 1 ppm. It has a 5.331(8), b 9.23(1), c 7.275(6) A, beta 104.15o; H. 3.5-4; Dcalc 3.44, Dobs. 3.08- 3.10; mean refr. ind. approx 1.61. Much of the fraipontite is admixed with sauconite, which may be forming from the fraipontite. XRF analysis of this material gave SiO2 32.8, Al2O3 10.9, MgO < 0.1, CaO 1.51, Na2O < 0.2, K2O < 0.02, TiO2 < 0.02, P2O5 < 0.02, MnO < 0.02, CuO 4.65, ZnO 39.9, ign. loss 13.9, = 103.7.-G.W.R.

Mineralogical Record↗
USGS1982

Stolzite from Tsumeb.

The world's largest known crystal of stolzite (1.3 X 1.3 X 2.5 cm) is described. It is associated with tennantite and quartz, and is from the Tsumeb mine, Tsumeb, Namibia. Forms present include (001), (111), (101), (122), and (212). Spectrographic analyses indicate a nearly end-member composition with Mo, Fe, Ba, Ca, and Mn present in trace amounts only. This stolzite fluoresces lemon- yellow and red in shortwave and longwave UV light, respectively.-G.W.R.

Mineralogical Record↗
USGS1982

Diamond collecting in northern Colorado.

The discovery of numerous diamond-bearing kimberlite diatremes in the N Front Range of Colorado and Wyoming is of both scientific and economic interest. Species recovered from heavy-mineral concentrates include Cr-diopside, spinel, Mg-ilmenite, pyrope and diamond. A nodule tentatively identified as a graphite-diamond eclogite was also found. -G.W.R.

Mineralogical Record↗
USGS1994

Plumboan crichtonite: from the Fazenda Guariba, Minas Gerais, Brazil

Senaite, Pb(Ti,Fe,Mn)21O38, a member of the crichtonite group, was first described from alluvial gravels near Dattas, Minas Gerais, Brazil. It was subsequently reported (always from alluvial stream gravels) from about seven additional localities. "Senaite' from the first in situ source in Brazil, at the Fazenda Guariba, Minas Gerais, Brazil was described by Cassedanne (1988). Approximately 20 crystals of "senaite' from the Fazenda Guariba were examined chemically and all were found to be plumboan crichtonite rather than senaite. -from Authors

Mineralogical Record↗
USGS1993

Edoylerite, Hg32+Cr6+O4S2 a new mineral from the Clear Creek claim, San Benito County, California

Edoylerite is a rare constituent of a small prospect near the long-abandoned Clear Creek mercury mine, New Idria district, San Benito County, California. It is most closely associated with cinnabar, from which it is a primary alteration product, in a host rock composed predominantly of quartz, chalcedony and ferroan magnesite. Edoylerite typically occurs as acicular to stellate crystal groups on and around corroded masses of cinnabar. The mineral is canary yellow to orangish yellow, and possesses a yellow streak and an adamantine luster. The crystallographic, physical and optical properties of edoylerite are described. -after Authors

Mineralogical Record↗
USGS1994

The French Creek Mine: St. Peters, Chester County, Pennsylvania

The French Creek mine has been a popular and prolific mineral collecting locality for over a century. Chalcopyrite occurs at the mine in spectacular specimens. Also notable are the fine cubic and octahedral pyrite crystals and octahedral magnetite crystals. -Authors

Mineralogical Record↗
USGS1996

Calcioaravaipaite: A new mineral and associated lead fluoride minerals from the Grand Reef mine, Graham County, Arizona

The Grand Reef mine in southeastern Arizona, best known to collectors for superb crystals of linarite, is also the type locality far a unique suite of lead fluoride minerals. Grandreefite, pseudograndreefite, laurelite, aravaipaite, and artroeite have been found nowhere else; added to this group is calcioaravaipaite, described here for the first time.

Mineralogical Record↗
USGS1995

A new U-Ti-Ca-HREE hydrated oxide and associated niobian rutile from Topaz Valley, Utah

In October of 1988, specimens of yellow and/or white acicular needles growing out of equant to platy hematite were collected from the east side of Topaz Valley. For the past five years, attempts have been made by all of the authors to completely characterize what is believed to be a new mineral species. Because of several major factors the space group, exact formula, and structure are still unknown. The potentially new mineral and some associated minerals are described here with the hope that elsewhere in the world better and more material exists that will allow complete characterization. -from Authors

Mineralogical Record↗
USGS1995

Pink topaz from the Thomas Range, Juab County, Utah

The Thomas Range is world-famous for its production of topaz Al2SiO4(F,OH)2, occurring in lithophysal cavities in rhyolite. Topaz Valley, at the southern end of the range, is perhaps the single most famous locality. While fine-quality, sherry-orange crystals to 5 cm or more in length occur at various localities, pale to medium pink crystals were first reported from the Thomas Range in 1934. The cause of the unusual coloration, unknown for 60 years, is now believed to be substitution of Mn3+ ?? Fe3+ for Al3+. -Authors

Mineralogical Record↗
USGS1999

The Zapot pegmatite mineral county

The Zapot pegmatite is currently being mined for mineral specimens (chiefly amazonite, topaz and smoky quartz in miarolitic cavities), for gemstones (topaz and smoky quartz) and for decorative rock (amazonite). The deposit is owned and operated by Harvey Gordon Minerals of Reno, Nevada, and is the only amazonite-topaz mining operation in the state. Thousands of specimens from this operation have reached the collector market.

Mineralogical Record↗
USGS2003

The petrographic microscope: Evolution of a mineralogical research instrument

The petrographic microscope, designed to observe and measure the optical properties of minerals as a means of identifying them, has provided a foundation for mineralogical and petrological research for more than 120 years. Much of what is known today in these fields is attributable to this instrument, the development of which paralleled an evolution of fundamental optical theory and its correlation with mineral structure and composition. This instrument and its related accessories have evolved through a range of models and designs, which are in themselves distinctive for their scientific function and elegant construction, and are today prized by collectors of scientific instruments.

Mineralogical Record↗
USGS2003

Goldquarryite, a new Cd-bearing phosphate mineral from the Gold Quarry mine, Eureka County, Nevada

Goldquarryite, idealized formula CuCd2Al3(PO44F2(H2O)10(H2O 2, structure-derived formula (Cu0.70???0.30??1.00(Cd1.68Ca0.32??2.00Al3 (PO44F2(H2O)10[(H2O 1.60F0.40]??2.00, is triclinic, space group P1, with unit-cell parameters derived from crystal structure: a = 6.787(1), b = 9.082(2), c = 10.113(2) A??, ?? = 101.40(1)??, ?? = 104.27(1)??, ?? = 102.51(1)??, V = 568.7(3) A??3, a:b:c: = 0.7473:1:1.1135, Z = 1. The strongest seven reflections in the X-ray powder-diffraction pattern are [d(A??)(I)(hkl)]: 9.433(100)(001); 4.726(30)(002); 3.700(30)(022); 3.173(30b)(122, 113, 120, 003); 3.010(30)(122, 212); 2.896(30)(211); 2.820(50)(022). The mineral occurs on a single specimen collected from the 5,425-foot bench, Gold Quarry mine, Eureka County, Nevada, as isolated clusters of radiating sprays of crystals and as compact parallel crystal aggregates, which are both found on and between breccia fragments. Sprays and aggregates never exceed 3 mm in longest dimension and typically average about 0.5 mm in size. Goldquarryite is a late-stage supergene mineral associated with opal, carbonate-fluorapatite and hewettite, on a host rock composed principally of brecciated and hydrothermally rounded jasperoid fragments which have been lightly cemented by late-stage silicification. Individual euhedral crystals are acicular to bladed, elongate [100], with a length-to-width ratio of approximately 20:1; the maximum size is 1.5 mm but most crystals do not exceed 0.4 mm in length. Forms are {010}, {001} major and {100} very minor. The mineral is pleochroic; translucent (masses) to transparent (crystals); very pale blue to blue-gray (crystals) or blue (masses); with a white streak and a vitreous to glassy luster. Goldquarryite is brittle, lacks cleavage, has an irregular fracture, and is nonfluorescent; hardness (Mohs') is estimated at 3-4; measured density is 2.78(1) g/cm3 (sink-float techniques using methylene iodide-acetone mixtures), calculated density is 2.81 g/cm3 (for formula and unit-cell parameters derived from crystal structure). Optically, it is biaxial positive, ?? = 1.570, ?? = 1.573, ?? = 1.578; 2V (meas.) = ???30??, 2V (calc.) = 76??; dispersion r < v, strong. Average electron-microprobe analysis: K2O = 0.17, CuO = 5.33, CaO = 1.25, NiO = 0.23, ZnO = 0.05, CdO = 26.24, Al2O3 = 15.22, V2O3 = 0.05, P2O5 = 28.04, F = 3.63, H2O (calculated assuming stoichiometry) = [22.19], -O = F = -1.53, total = 100.87 weight %, corresponding to [(Cu0.66Ni0.03Zn0.01) ??0.70.

Mineralogical Record↗