New Utah Minerals – Cannonite, Fangite, Gillulyite, and Tooeleite

By Chris Kelson

Cannonite, Bi2O(OH)2SO4
Cannonite is a bismuth hydroxide sulfate found in the Tunnel Extension mine, Ohio mining district, Piute County. It is a rare mineral associated with quartz gangue and is characterized by colorless, transparent crystals.The mineral has an adamantine luster and is brittle, with uneven to conchoidal fracture.

Associated minerals include cuprobismutite, bismuthinite, and covellite. Cannonite was named for B.B. Cannon, who first recognized the mineral.

Miscellaneous data: hardness = 4; density = 6.515 g/cc

Fangite, Tl3AsS4
Fangite is a thallium arsenic sulfosalt found at the Mercur gold deposit in the southern Oquirrh Mountains of Tooele County. It forms in vugs with pyrite an other sulfide material of complex composition.

Fangite exhibits a deep-red to maroon color, and although no streak was obtained from natural fangite, synthetic fangite has an orange streak. Fangite is translucent but tarnishes to a nearly metallic luster. Crystals have relatively flat surfaces and conchoidal fracture.

Associated minerals include realgar, orpiment, pyrite, and other sulfides. Fangite was named for Jen-Ho Fang in honor of his numerous contributions to crystallography, crystal chemistry, and geostatistics.

Miscellaneous data: hardness = 2.0 – 2.5; density = 6.185 g/cc

Gillulyite, Tl2(As,Sb)8S13
Gillulyite is one of several thallium minerals that are found in the Mercur gold deposit, Tooele County. It is found in vuggy masses of barite, in barite and calcite veins, and in the silty, carbonaceous limestone host.

Gillulyite has a deep-red color and a red streak. It is translucent but tarnishes rapidly to a darker red or blue. Gillulyite forms very small, slender, prismatic crystals and has one perfect cleavage that is obvious on all specimens.

Associated minerals are barite, calcite, orpiment, realgar, lorandite, raguinite, and pyrite. Gillulyite was named in honor of the late James C. Gilluly, author of the U.S. Geological Survey Professional Paper 173, Geology and Ore Deposits of the Fairfield and Stockton Quadrangles, Utah.

Miscellaneous data: hardness = 2.0 – 2.5; density = 4.022 g/cc (meas)

Tooeleite, Fe8-2x[(As1-xSx)O4]6 . 5H2O
Tooeleite is found on waste dumps of the former gold and arsenic mines in the Gold Hill district, western Tooele County. Oxidation of the quartz-diopside host rock produced massive scorodite (a lesser ore of arsenic) containing voids, some lined with jarosite, and both minerals are coated with tooeleite crusts up to 10mm thick.

Tooeleite crystals form elongate blades up to 1cm, and are translucent with a greasy luster. Hand specimens are orange with an orange streak. Tooeleite is a name derived from the locality.

Miscellaneous data: hardness = 3; density = 4.238 g/cc (meas)

Jambor, J.L., and Burke, E.A.J., 1993, New Mineral Names: American Mineralogist, v. 78, nos. 7 and 8, p.845.

Wilson, J.R., Gupta, P.K.S., Robinson, P.D., and Criddle, A.J., 1993, Fangite, Tl3AsS4, a new thallium arsenic sulfosalt from the Mercur Au deposit, Utah, and revised optical data for gillulyite: American Mineralogist, v. 78, nos. 9 and 10, p. 1096.

Wilson, J.R., Robinson, P.D., Wilson, P.N., Stanger, L.W., and Salmon, G.L., 1991, Gillulyite, Tl2(As,Sb)8S13, a new thallium arsenic sulfosalt from the Mercur gold deposit Utah: American Mineralogist, v. 76, p. 653.

Wilson, J.R., and Wilson, P.N., 1990, Occurrence and paragenesis of thallium sulfosalts and related sulfides at the Barrick Mercur gold mine, Utah: Utah Geological Association Publication, no. 18, p. 78.

from Survey Notes, v.26, no.2-3, May 1994