Whole rock major, minor, and trace element geochemistry of the upper part of the Mount Emmons-Redwell porphyry molybdenum (Climax-type) deposit, Redwell Basin, Crested Butte, Colorado

This U.S. Geological Survey (USGS) data release provides whole rock major, minor, and trace element geochemical data from the fluorine-rich Mount Emmons-Redwell porphyry molybdenum (Climax-type) deposit (Mt. Emmons-Redwell deposit), located approximately 5.6 km (3.5 mi) northwest of Crested Butte, Colorado. The Mt. Emmons-Redwell deposit partly underlies Redwell Basin on the northwest flank of Mount Emmons in the west-central region of the Colorado Mineral Belt. Mineralization of the Mt. Emmons-Redwell deposit occurs at depth as vein, veinlet, stockwork, and fracture-hosted Climax-type mineralization [308 Mt at 0.32% Mo (Galey, 1978; Guarnera and Anderson, 2007)], and is associated with the Mt. Emmons igneous complex. Samples were collected by research staff from the USGS Geology, Geophysics, and Geochemistry Science Center (GGGSC) and Colorado School of Mines from outcrops, waste rock piles, and drill core from the upper part of the deposit, the associated base metal vein system, and the surrounding hydrothermally altered to unaltered country rock.

Laboratory analyses of samples were conducted under independent analytical contract, with oversight by the USGS. Major and minor elements Al, Ba, Ca, Cr, Fe, K, Mn, Na, P, Si, Sr, Ti, and V were determined using wavelength dispersive X-ray fluorescence spectrometry (WDXRF) methods, and are reported as oxide equivalents. Major, minor and trace elements Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho, In, K, La, Li, Lu, Mg, Mn, Mo, Nb, Nd, Ni, P, Pb, Pr, Rb, Sb, S, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, and Zr were determined using inductively coupled plasma-optical emission-mass spectroscopy (ICP-OES-MS) methods. Fe2+ was determined using acid digestion and titration (Titr) analysis. F was determined using ion-selective electrode (ISE) analysis. Loss-on-ignition (LOI) was determined gravimetrically after sample combustion.

References cited:
Galey, J.T., Jr., 1978, Mount Emmons molybdenite deposit Gunnison County, Colorado: Unpublished report for Amax Exploration, Inc., Denver, Colorado, 70 p.

Guarnera, B.J., and Anderson, M.A., 2007, Technical report on the Lucky Jack Molybdenum Deposit Crested Butte, Colorado, U.S.A: Unpublished report prepared for Kobex Resources, Ltd. by Behre Dolbear & Company (USA), Inc., 93 p.