ARTSMITHITE, A NEW Hg1+-Al PHOSPHATE-HYDROXIDE FROM THE FUNDERBURK PROSPECT, PIKE COUNTY, ARKANSAS, U.S.A.

Abstract

(732,640,204). The mineral occurs as a colorless-to-white matted nest, approximately 3 ϫ 1 mm in size, of randomly scattered fibrous to acicular crystals at the Funderburk prospect, Pike County, Arkansas, U.S.A. Associated minerals on the holotype specimen are quartz, goethite, dickite and cinnabar; other minerals reported from the locality include barite, calcite, calomel, eglestonite, fluorapatite, galena, livingstonite, native mercury, metacinnabar, montroydite, perhamite, pyrite, siderite, stibiconite, stibnite and terlinguaite. Artsmithite is a secondary phase most probably formed from the breakdown of primary cinnabar and apatite. Individual needles are elongate [001], colorless, transparent, with a length-to-width ratio in excess of 100:1, and they average about 0.5 mm in length. Artsmithite is vitreous, with an off-white to cream streak, no obvious cleavage, irregular fracture; it is nonfluorescent, and the needles are flexible. D(calc.) is 6.40 g/cm 3 for the formula inferred from the crystal-structure analysis. It is biaxial positive, and all indices of refraction exceed 1.80; 2V (meas.) 60°; r < v, distinct; length slow with Z ≈ c. (732,640,204). Le minéral se présente en amas de cristaux aciculaires incolores ou blancs non orientés, mesurant environ 3 ϫ 1 mm, à l'indice Funderburk, comté de Pike, en Arkansas, aux Etats-Unis. Lui sont associés sur l'échantillon holotype: quartz, goethite, dickite et cinnabre; on a aussi trouvé barite, calcite, calomel, eglestonite, fluorapatite, galène, livingstonite, mercure natif, métacinnabre, montroydite, perhamite, pyrite, sidérite, stibiconite, stibnite et terlinguaïte à cet endroit. La artsmithite est une phase secondaire, tout probablement le résultat d'une déstabilisation du cinnabre et de la fluorapatite.

Mercury (Hg) mineral evolution: A mineralogical record of supercontinent assembly, changing ocean geochemistry, and the emerging terrestrial biosphere

“…These Hg deposits must postdate their host lithologies, but ages of emplacement are not always provided in the literature. For example, the Hg mining district of Pike County, Arkansas, is hosted in Carboniferous sediments (359-299 Ma;Lowe 1985;Roberts et al 2003a), but we have been unable to find a reliable age range for the subsequent Hg mineralization.…”

“…For example, perroudite (5HgS•Ag 4 I 2 Cl 2 ) and capgaronnite occur by alteration of Hg-and Ag-bearing tennantite (Cu 12 As 4 S 13 ) or tetrahedrite (Cu 12 Sb 4 S 13 ) by halide-bearing solutions of marine origin (Sarp et al 1987). Similarly, corderoite and kenhsuite (the α and γ forms of Hg 3 S 2 Cl 2 , respectively), radkeite (Hg 3 S 2 ClI), eglestonite {[Hg 1+ ] 6 O(OH)Cl 3 }, and many other Hg minerals occur as hydrothermal alteration products of cinnabar (Tunell et al 1977;Vasil'eva and Lavrent'ev 1980;Roberts et al 1981Roberts et al , 1990Roberts et al , 1993Roberts et al , 2003aRoberts et al , 2005McCormack et al 1991;McCormack and Dickson 1998;Pervukhina et al 2008). For example, perroudite and danielsite [(Cu,Ag) 14 HgS 8 ] occur in a supergene assemblage in gossan at Coppin Pool, Western Australia, hosted by sedimentary host rocks of the Fortescue Group (Nickel 1985(Nickel , 1987Sarp et al 1987), which has been dated 2.765-2.697 Ga elsewhere in the Hamersley Basin (Arndt et al 1991).…”

The crystal structure of gianellaite, [(NHg2)2](SO4)(H2O)x, a framework of (NHg4) tetrahedra with ordered (SO4) groups in the interstices

“…The approximate atomic arrangement was determined, with (NHg 4 ) tetrahedra sharing corners to form a framework of the anti-cristobalite (= cuprite) structure, but the location of the sulfate group was not determined. As part of our continuing interest in Hg minerals Hawthorne, 2003, 2009;Cooper et al, 2013;Hawthorne et al, 1994;Roberts et al, 2002Roberts et al, , 2003aRoberts et al, ,b, 2005, the crystal structure of gianellaite has been refined in order to resolve the distribution of the interstitial species.…”