Geology topics

Nancy M. Conklin

Publications and source records attributed to Nancy M. Conklin.

4 recordsLinked to original sources

USGS1988

COEXISTING GALENA, PbS//S//S AND SULFOSALTS: EVIDENCE FOR MULTIPLE EPISODES OF MINERALIZATION IN THE ROUND MOUNTAIN AND MANHATTAN GOLD DISTRICTS, NEVADA.

Studies of galena and Pb-Bi-Ag-Cu(Hg) sulfosalts of varied compositions in the Round Mountain and Manhattan gold districts of Nevada corroborate the occurrence of several distinct mineralized systems characterized by different mineral compositions and assemblages. The different episodes of mineralization are related to different Cretaceous and Tertiary magmatic-hydrothermal events, although the assignment of specific mineral compositions and associations with dated mineralized systems is still incomplete. At the Fairview mine, galena associated with Pb-Bi-Ag sulfosalts and simple sulfides occurs as intergrowths of discretely different composition controlled by silver and bismuth content. A galena-type phase (Pbs//s//s) with solid solution toward matildite, AgBiS//2(composition Gal//6//0Mat//4//0) was found. If silver and, to a lasser extent, bismuth are absent, the galena formed will be almost pure PbS. Some minor antimony may substitute for bismuth. This study confirms a linear relationship between a cell edge and Ag-Bi(Sb) content for galena containing less than about 15 wt. percent Ag and Bi(Sb).

Canadian Mineralogist↗

USGS1980

Gamma-ray spectrometric and semiquantitative spectrographic analytical data of the thorium and rare-earth disseminated deposits in the southern Bear Lodge Mountains, Wyoming

No abstract available.

Wyoming↗

USGS1977

Rare earths, thorium, and other minor elements in sphene from some plutonic rocks in west-central Alaska

Sphene is an abundant accessory mineral in some abnormally radioactive plutonic rocks in west-central Alaska. Seven samples of sphene from four different areas in west-central Alaska contained from 20350 to 39180 parts per million total rare earths and 390 to 2000 ppm thorium. The lanthanide content in six of the seven sphenes is chiefly the light rare earths and is similar to that of crustal abundance; a seventh sphene from the Darby Mountains, however, contains above average amounts of the heavy rare earths. A comparison of the lanthanide distribution in sphene from several areas indicates that the structure of sphene will accommodate whatever lanthanides are available when the mineral crystallizes. The amount of thorium and rare earths in sphene is also affected by the presence of other accessory minerals. Sphene in rocks containing either allanite or zircon has a lower thorium content than in rocks that do not contain allanite or zircon. Sphene, because of its abundance, may contain the greater part of the rare earths and thorium in some of the plutonic rocks of west-central Alaska.

Alaska↗

USGS1973

Galkhaite, (Hg,Cu,Tl,Zn) (As,Sb)S2, from the Getchell mine, Humboldt County, Nevada

The first reported occurrence in the United States of galkhaite (Hg,Cu,Tl,Zn)(As,Sb)S 2 is at the Getchell mine, Humboldt County, Nev. The mineral occurs as brownish-black cubes associated with graphite, pyrite, and realgar. In polished section galkhaite is grayish white and isotropic with a deep-red internal reflection; reflectivity at 590 nm is 21.6 percent. Spectrographic analysis gave Hg 42 percent, Cu 5 percent, Zn 1.5 percent, Fe 0.7 percent, Tl 5 percent, As 24 percent, Sb 0.3 percent, and S (by difference) 21.3 percent. The mineral is cubic, a=10.36, and the strong lines of the X-ray powder pattern are 2.99 (100), 4.21 (90), 2.76 (80), 1.831 (70), 7.25 (60), 2.58 (40), 1.561 (40). The pattern is very similar to that of tetrahedrite except for the strong lines at 7.25, 4.21, and 2.76.

Nevada↗