Gold in Minerals and the Composition of Native Gold
Gold in Minerals and the Composition of Native Gold
By Robert S. Jones and Michael Fleischer
GEOLOGICAL SURVEY CIRCULAR 612
Washington 1969 United States Department of the Interior WAl.TfR J. HICKEL, Secretary
Geological Survey William T. Pecora, Director
Free on application to the U.S. Geological Survey, Washington, D.C. 20242 CONTENTS
Page Abstract ------~------1 Introduction ------1 General geochenrlcal considerations ------1 Gold in minerals ------_ 2 Composition and the fineness of gold ------___ 13 References cited ------·------______15
TABLES
Page 'fABLE 1. Major gold-bearing minerals ------__ 2 2. Analyses of precious metals in minerals made before 1955 ______. _ 3 3. Analyses of gold in minerals made since 1954 ------10 4. Variation in fineness of gold with depth, Lily mine, Transvaal, South Jlfrica ------14 5. Fineness of mill bullion prior to 1882 at the Homestake nrlne, South Dakota ------15
Ill
GOLD IN MINERALS AND THE COMPOSITION OF NATIVE GOLD
By ROBERT S. JONES and MICHAEL FLEISCHER
ABSTRACT much lower concentrations in the sulfiie phase, Gold occurs in nature mainly as the metal and as and occurs in much lesser amount~ in the various alloys. It forms complete series of solid solu silicate phase. Gold occurs in natur~ mainly tions with silver, copper, nickel, palladium, and as the metal and as various alloys, especially platinum. In association with the platinum metals, gold with silver, and as intermetallic co:'llpounds. occurs as free gold as well as in solid solution. Laboratory studies show that gold can form The native elements contain the most gold, followed by the sulfide minerals. Several gold tellurides are complete series of solid solutions with silver, known, but no gold selenides have been reported, and copper, nickel, platinum, and palla:dium. Gold only one sulfide, the telluride-sulfide mineral nagyagite, is commonly present in association with plati ii:; known. num metals; most microscopic stuc"ies have The nonmetallic minerals carry the least gold, and shown that free gold is present in platinum, the light-colored minerals generally contain less gold than the dark minerals. but a recent electron-probe analysis of ferro Some conclusions in the literature are conflicting in platinum shows uniform distributioi' of gold regard to the relation of fineness of native gold to its ( Ottemann and Augustithis, 1967). This distri position laterally and vertically within a lode, the bution indicates that gold and platinum aTe nature of the country rocks, and the location and size present in solid solution. of nuggets in a streambed, as well as to the variation of fineness within an individual nugget. Several gold tellurides are known (table 1), but no gold selenides have been repC'...-ted, and INTRODUCTION the only minera~ in which gold is certainly combined with sulfur is the telluride-sulfide, This report on the occurrence of gold in nagyagite. Gold commonly occurs in sulfide minerals and on the fineness of native gold minerals, but largely, if not entirely, as the was prepared as background material for the free metal; it is uncertain whether any gold Heavy Metals program of the U.S. Geological occurs in these minerals in true isomorphous Survey, an intensified program of research substitution. on new sources of heavy metals, including gold. It is even less likely that gold is present in ionic substitution in silicate miner·als. Man GENERAL GEOCHEMICAL CONSIDERATIONS tei and Brownlow (1967) state, "Tl'e concen tration of gold in the various minerals is proba Gold belongs to group Ib of the periodi.c bly due to an inclusion or entrappinr-- phenom table, as do silver and copper. Its atomic num ena rather than to ionic substitutior. Because ber is 79, and atomic weight is 197.0; it con of its oxidation potenti.al, it would 1~<~ difficult sists of a single isotope. Its metallic radius for gold to become oxidized and thus be able is 1.44A., univalent ionic radius 1.37A., and to take part tn ionic substitution. Krauskopf trivalent ionic radius 0.85A. (1951) states that simple ionic goli can not Gold is strongly siderophilic and somewhat exist in geological environments, alth('mgh com chalcophilic; that is, it tends to be co,ncen plex ions containing gold may form. Ringwood trated in the metallic phase of meteorites, with (1955) points out that Au+, because of its
1 large electronegativity, would form a very been made by more sensitive methods, mostly weak covalent bond, and one which would pre by neutron activation, than the older ones, fer not to form. Thus the gold of a crystallizing and values as low as 0.0003 ppi1. (part per magma tends to concentrate in the residual million) are reported. However, comparatively fluids. The factors which would control the few neutron activation analyses . of rock-form amount of gold entrapped in a given mineral ing minerals have been reportei in recent would be the concentration of gold in the years. The older analyses tend to be significant magma at the time of crystallization and the ly higher than more recent analyses of the type of crystal structure formed by the min same minerals. The highest gold values listed eral." in tables 2 and 3 are reported for the native Helgeson and Garrels (1968), on the basis elements; next highest are for the sulfide min of thermodynamic calculations, think that all erals. but marginal or low-grade hydrothermal native TABLE 1.-Major gold-bearing minerals gold deposits form above 175°C and, at ele vated temperatures, most hydrothermal solu Gold Au. Cubic, sp gr 19.3 (pure Au), decreasing with ircreasing con tions are probably distinctly acid. They believe tent of Ag. Form!;; a complete that gold is present primarily in the form series of solid solutions with silver of aurous chloride complexes in contrast to (see electrum and silver, below); the low-temperature considerations of Kraus commonly contains 10-15 percent Ag. Also reported in percent: Cu kopf (1951) and Cloke and Kelly (1964) who (ma..."X: 20.4), Fe (ma.x 0.1), rarely suggest that the aqueous species AuC17 is Bi (max 2.9), Sn (max 0.3), Ph the principal form of dissolved gold in hydro (ma..."X: 0.2), Zn (max 0.8), AI (max thermal solutions. 0.10), Mn (max 0.002). See sec Goni, Guiiiemin, and Sarcia (1967) have tion "Composition and Fineness of Gold." investigated the stability of colloidal suspen Varieties: sions of gold and the formation of nuggets. Electrum, (Au,Ag), argentian geld with >20 Stable colloidal suspensions of ionic and even percent Ag. metaiiic gold can form which can be floccu Porpezite, (Au,Pd), palladian go1d with 5-10 lated to form nuggets. Textures common in percent Pd. gold deposits can be reproduced in gold films Rhsxlite, (Au,Rh), rhodian gold(?) with 34-43 percent Rh. formed by the diffusion of gold solutions Auricupride (cuproauride) has generally been through silica gel. considered to be a solid solution of gold in Gold occurs in notable amounts in hydro copper, near AuCua in. composWon. Ramdohr thermal veins and in placer deposits, and to (1967) states, however, that study of "red gold" from Laksia, Cyprus, has shown the a much lesser extent in pegmatites and con presence of three· distinct phases Au-Cu solid tact metamorphic deposits. Commo.n minerals solutions, the compound AuCua with a _associated with gold in veins are quartz and characteristic violet color, and the compound pyrite. Some other common minerals associ Au Cu. ated with gold (Lincoln, 1911; Schwartz, 1944) Aurosmirid, aurosmiridium ( =aurian osmiri are pyrrhotite, arsenopyrite, chalcopyrite, sphal dium) Au 19.3 percent. ProbabJy a mixture containing gold. erite, galena, molybdenite, tellurides, selenides, (Palache and others, 1944, p. 111). magnetite, scheelite, feldspar, sericite, biotite, Silver (Ag,Au). Aurian silver, with 0-50 chlorite, amphiboles, garnet, tourmaline, car percent Au. bonates, and fluorite. Kiistelite=aurian silver. Gold-amalgam A112Hga(?) GOLD IN MINERALS Au 34.2-41.6 percent. Maldonite Au2Bi. Cubic. Minerals that have been reported to contain Au 64.5-65.1 percert; Bi 34.9- major amounts of gold are listed on table 35.5 percent. 1. Many analyses have been made for some Aurostibite AuS~. Cubic, pyrite tYf<:'\. of the precious metals in minerals that con Au 43.5-50.9 percent. Krennerite AuTe2. Orthorhombic. tain little gold;: those made before 1955 are Au 30.7-43.9 percent. listed in table 2 and those made since 1954 M iillerine = Krennerite are in table 3. The more recent analyses have Speculite = Krennerite (?)
2 TABLE l._JMajor gold-bearing minerals-Continued TABLE 1.-Major gold--bearing m.inerals-Concluded Calaverite AuTe2. Monoclinic. Hessite Ag2Te. Monoclinic, pseudocubic. Au 39.2-42.8 percent. Reported to contain as much as Coolgardite =a mixture of calaverite, coloradoite, 4.7 percent Au. and sylvanite. Montbrayite Au2Tea. Triclinic. Sylvanite (Au,Ag) Te2, with Au :Ag usually Au 38.6-44.3 percent. nearly 1:1, that is, AgAuTe4. Nagyagite PbsAu(Te,Sb)4Ss-s( ?) • Monoclinic. Monoclinic ( ?) . Au 24.25-29.9 percent. Au 7.4-10.2 percent. Goldschmidtite= Sylvanite. Silberphyllinglanz = N agyagite. Kostovite CuAuTe4 Blatterine = N agyagite. Au 25.2 percent (Terziev, 1966). Aurobismuthinite (Bi, Au,Ag) sSs ( ?) Petzite AgaAuT~ Au 12.3 percent; Ag 2.3 percent. Au 19.0-25.2' percent. Probably a mixture (Palache and Antamokite=a mixture of petzite and altaite. others, 1944 p. 278).
TABLE 2.-Analyses of precious metals in minerals made before 1955 [Minerals containing higher amounts of gold are listed in table l. N. D., not determined]
Gold Silver Platinum Mineral and locality (ppm) (ppm) (ppm) Remarks Reference
Elements
Arsenic, As Germany, Andreasberg, Harz ___ _ 150 >1,000 20 One sample __ Noddack and No·ldack (1931). Copper, Cu Norway, Kviteseid ------200 >1,000 .3 Two samples _ Do. Iridosmine, ( Os,Ir) Australia, New South Wales _____ 800 >1,000 Eight samples Do. U.S.S.R., Urals ------>1,000 600 >1,000 Do. Iron, (Fe,Ni) Greenland, Ovifak, Disko ______1-5 5-10 5 In basalt ____ Goldschmidt and Pe...,ers (1932). United States: Cal).yon Diablo, Ariz ______5 5 10-100 In meteorite _ Do. Holbrook, Ariz ------10 1 10-100 _____ do ____ _ Do. Mexico Coahuila ------~------1-5 5 10-100 _____ do ---- Do. Chile, Corrizatillo ------5-10 5-10 10 In meteorite _ Do. Germany, Biihl, near Kassel ______.5 5-10 .2 In basalt ___ _ Do. Czechoslovakia, Knyahinya ______10 1 10-100 In meteorite _ Do. Portugal, Sao Juliao de Moreira __ 10 5 10-100 _____ do ____ _ Do. Platinum, Pt Brazil ------> 1,000 >1,000 >1,000 One sample __ Noddack and Ncddack (1931). U.S.S.R., Urals ------500 200 >1,000 Eleven sam Do. ples. Platiniridium, (Ir,Pt) Brazil ------ 200 >1,000 One sample __ Do. Schreibersite, (Fe,Ni) aP Portugal, Sao J uliao de Moreira __ 1 10 1.2 In meteorite. Gold ""<'hmidt and Two samples. Peters (1932).
Sulfides, arsenides, selenides, and tellurides
Domeykite, CuaAs Mexico, Paracatas 25 >1,000 5 One sample __ Noddack and Noddack (1931). Argentite, AgsS Germany, Freiberg 200 >1,000 4 Two samples _ Do.
3 TABLE 2.-Analyses of precious metals in minerals made "efore 1955-ContinU6d
Gold Silver Platinum Mineral and locality (ppm) (ppm) (ppm) Remarks lkoference
Sulfides, arsenides, selenides, and telluride.-Gontinued
Berzelianite, C111Se Sweden, Skrikerum 100 >1,000 10 One sample __ Noddack and Nod
South Africa, Transvaal ------1-10 10-100 From Meren Schnei(i"erhohn sky Horizon (192S). on Schild padnest, Rustenburg district. Content of other ele ments: Cu, Co about 0.1 percent; Pa, 10-100 ppm; Ru, Rh, Ir, 0.1- 1 ppm; Os, a trace. 4 TABLE 2.-Analyses of precious metals in minerals made before 1955-Continued
Gold Silver Platinum Mineral and locality (ppm) (ppm) (ppm) Remarks Reference
Sulfides, arsenides, selenides, and tellurides--Continued
Troilite, FeS United States, Canyon Diablo, Ariz_ 0.5 10 0.5 In meteorite - Goldsclmidt and Peter~ (1932). Mexico: Coahuila ------ 1-5 5 1-10 _____ do _____ Do. Ixtlahuaca ------.2 15 6 _____ do _____ Noddack and Nodcack (1931). Chile, Corrizatillo ______.5 10 .2 _____ do _____ Goldscl midt and Peters (1932). Esthonia, Tennasilm 0 5 .3 _____ do _____ Noddar.k and Nodc"ack (1931). Niccolite, NiAs Germany: Eiselben ______1 1()..-100 ------Goldschmidt and Pete~s (1932). Klettenberg, Sauerland ______10 10 .2 ------Do. Austria, Schladming, Styria ____ _ •5 100 ------Do. Pentlandite, (Ni,Fe,Co) eSs Norway, Espedalen ______6 140 2 Two samples - Noddack and Nodrlack (1931). Germany, St. Blasien, Schwarzwald_ .5 10-100 .2 ------Goldschmidt and Pete~s (1932). South Africa, Rustenburg district, Transvaal ------1.0 5-10 ------Schnei/lerhohn and Morftz (1931). Siegenite, (Co,Ni)sS4 Germany, Miisen near Siegen ___ _ 1 >1,000 .5 ------Goldsc"midt and Peters (1932). Pyrite, FeS2 Norway: Setesdalen .4 10 Fifteen sam- Nodda~k and pies. Noddack (1931). Sulitjelma ------.4 70 . 3 ------Do. Italy: Calceranica ------1.1 ------Mingur.zi (1947). Libiola, Genova Province ______.33 Two samples _ Do. Boccheggiano, Grosseto ______.12 ------Do. Chuch e Servetie ______.95 ------Do. Pestarena ------ 200 ------Do. Lavanchetto ------20 ------Do. Do. Alfenza ------6.5 Crystalline aggregate contained 12 ppm Au and a crys- tal con- tained 0.93 ppm Au. Two sam- pies. South Africa: Rustenburg district,Transvaal __ _ 5-10 10-50 Nickeliferous_ Schne~
Gold Silver Platinum Mineral and locality (ppm) (ppm) (ppm) Remarks Reference
Sulfides, arsenides, selenides, and tellurides--Continued
Cobaltite, CoAsS Canada, Cobalt, Ontario ______6 6 0.1 ------Gold:-1~hmidt and Pe+ers (1932). Norway, Skutterud ------10 200 2 One sample -- Nodcack and Ncddack (1931). .6 1 ------Gold:~ehmidt and Pe~ers (1932). Sweden, Tunaberg ------ •6 10 .5 ------Do . Germany: Dreikonigsstollen Buchholz, Saxony •8 10 .1 ------Do • Gliicksbrunn, Altenstein, Sachsen-~eine ------ 3 5 •1 ------Do • Gersdorffite, NiAsS Germany: ~lisen, near Siegen ------ 10-100 10-100 .1 ------Do. Friedensgrube, Lichtenberg, Oberfranken ------ 10-100 10-100 .1 ------Do. Lobenstein, Vogtland, Thiiringen_ 5 1 ------Do. Michaelis Fundgrube, Triebel, near Zwickau ------10-100 10-100 .1 ------Do. Ullmannite, NiSbS Germany: Miisen, near Siegen ------20 20 •5 ------Do . Salchendorf, near Siegen ______10 100------Do. 1,000 Landeskrone, Willnsdorf, near Siegen ------ .6 10-100 .2 ------Do• Saffiorite, CoAs2 Germany: Schneeberg, Saxony ------ .8 10-100 ------Do. Dachsberg, near Riechelsdorf 6 .5 •1 ------Do . Rammelsbergite, NiAs2 Germany, Gessellschafter Zug, Schneeberg, Saxony ______.3 6 ------Do. Marcasite, FeS2 Germany, Westphalia ______4 100 .1 One sample __ Nodd~~k and Nocdack (1931). Arsenopyrite, FeAsS Norway, Skutterud ------ 8 90 •4 Four samples_ Do . Germany, Ehrenfriedersdorf, Saxony ------.6 10 ------Golds<'!hmidt and Peters (1932) 0 Molybdenite, ~oS2 United States, Climax, Colo ______.06 100 .05 ------Do. Australia, Kingsgate, Glenn Innes, New South Wales ------1-10 100 •02 ------Do . Czechoslovakia, Zinnwald ______.1 .2 •05 ------Do . Germany: Sadisdorf near Schmiedeberg, Saxony ------5 10-100 1 ------Do. Altenberg, Saxony ______.2 2 .2 ------Do . Norway: Telemarken ------.6 4 .04 Three samples Do. Sorumsassen near Drammen ___ _ .6 10-100 .05 ------Do. Rade, 0stfold ______•05 10 ------Do . Undalen ______.06 >100 With chalco- Do. pyrite.
6 TABLE 2.-Analyses of precious metals in minerals made before 1955-Continued
Gold Silver Platinum Mineral and locality (ppm) (ppm) (ppm) Remarks Ref~renee
Sulfides, arsenides, selenid£s, and tellurides-Continued
Skutterudite, CoAss Germany: Niederrasmstadt near Darmstadt_ 0.3 1,000 Goldschmidt and Peter"' (1932). Riechelsdorf, Hessen ______2.7 10 Two samples _ Do. Bieber, Hessen ______.1 1-5 Do. Frauenbreitunger, Saxony- ]deiningen ______.8 10-100 Do. Schneeberg, Saxony ______.5 100- Do. 1,000 Hasserode, Harz ______5 10 Do. Austria, Schladming, Styria ______.8-.5 5 Do.
Sulfosalts
Tetrahedrite, CuuSb4S1s England, Cornwall ______8 >1,000 2 Noddack and Noddack (1931). Austria, Tyrol ______60 >1,000 .2 Seven samples Do. Germanite, Cua(Ge,Fe)S4 South-West Africa, Tsumeb -----~ 40 800 .2 One sample __ Do. Enargite, CuaAsS4 United States, Butte, Mont ______1& >1,000 .8 _____ do ____ _ Do. Argyrodite, AgsGeSs Bolivia ------90 >1,000 0 _____ do ____ _ Do.
Halides
Halite, N aCl England, Cheshire ______0.103 N.D. N.D. Two samples_ Liversiige (1897). Germany, Stassfurt ______.132 N.D. N.D. One sample __ Do . Sylvite, KCl Germany, Mecklenburg ______. 003 N.D • N.D. _____ do ----- Friedri ~k ( 1906) . Carnallite, KMgdla: 6H20 Germany, Bernburg ______. 012 N.D. N.D . ----- do ----- Do.
Simple oxides
Pyrolusite, Mn02 Czechoslovakia, Platten, Bohemia __ 0.2 4 10 Four samples_ Noddack and Nodc.11ek (1931). Cassiterite, SnOs Bolivia, Potosi ------.5 10-100 ·------Goldscl midt and Pete:--s (1932). Indonesia, Bangka Island ______.5 10 ------Do. Germany, Breitenbrunn near Zwickau, Saxony ______.5 10 Three samples Do. Czechoslovakia, Schonfeld near Schlaggenwald ------ .5 5 ------Do. South-West Africa: Sandamab ------ .5 10 .2 ------Do . Nubeb ------.5 1 •2 ------Do .
7 TABLE 2.-A"'Z.alyses of precious metals in minerals made before 1955-Contm:ued
Gold Silver Platinum Mineral and locality (ppm) (ppm) (ppm) Remarks Reference
Oxide!f eontainintr uranium, thorium, or zirconium
Uraninite, UOs Norway, Brevik ------0.1 2 0.2 One sample __ N odd ""ek and No·Jdack (1981). Czechoslovakia, Jaehymov ------ .03 5 Two samples _ Do.. Thorianite, ThOs Ceylon ------.05 2 •1 One sample -- Do •
Oxides C4ntainintr OB
Psilomelane, (Ba,HsO )sMnsOto Germany, Harz ------50 2 Two samples _ Noddack and Noddack (1981).
Multiple oxides
Chromite, (Mg,Fe)sCrO, United States: Mineral Hills, Pa ------0.2 1 1 Golds~hmidt and Pet1rs (1982). Lancaster County, Texas, Pa __ _ .2 1 Do. Norway, Feragen, Bebiet ------ .2 1 Do. Hausmannite, MnaO, Sweden, Li.ngban ------.1 10 Two samples _ Noddr~k and Noc..fack (1981).
Multiple oxides eontainintr Nb, Ta, and Ti
Columbite, (Fe,Mn) (Nb,Ta)sOe Norway, Arendal ------0.05 2 8 Twenty-three Nodd~ek and samples. Nod~ack (1981).
Silieates
Plagioclase, (Na,Ca) (Al,Si)2Sb0s South Africa, Rustenburg district, TransvaaJ ------ <0.5 <0.5 Schnei~erhohn and Pyroxenes: Mor'tz (1981). Bronzite, (Mg,Fe)SiOs South Africa, Rustenburg district, Transvaal ------ 1-5 Do. Diallage, Ca(Mg,Fe)SisOe South Africa, Rustenburg district, Transvaal ------ .5 1-5 Do. Olivine, (Mg,Fe)sSiO, South Africa, Rustenburg district, Transvaal ------.5 1.0 Do. Gadolinite, YsFeBe.SisOe Norway, Iveland ------.2 4 2 Nodda~k and Noddack (19:ll) Arandisite, (tin silicate?) South-West Africa, Arandis ______.5 5 .2 Goldsc:'tmi<~t a'ld Peters (1932). Hellandite, silicate of Ca and Y Norway, Kragero ------.1 .1 One sample -- Noddaek and Noddack (1981).
8 TABLE 2.-Analyses of precious metals in minerals made before 1955-Continued
Gold Silver Platinum Mineral and locality (ppm) (ppm) (ppm) Remarks R(>ference
Phosphates Triplite, (Mn,Fe)J(PO.)F South-West Africa, Sandamab ___ _ 0.5 5 0.2 ·------Goldschmidt and Perers (1932).
Nitrates
Soda Niter, NaNOa Chile ------0.110 N.D. N.D. One sample -- Liversidge (1897).
Sulfates
Anhydrite, caso. Germany, Pllimnitz ------0.007 N.D. N.D. One sample-- Fried~ick 1906). Gypsum, CaSO. ·2Hs0 United States: Salina, N.Y ------.083 N.D. N.D. Silurian. One Linco1n (1911). sample. Grand Rapids, Mich ------.083 N.D. N.D. Mississippian. Do. One sample. Kainite, KMg(SO.)Cl·SHsO Germany, PIOmnitz ------•003 N.D. N.D• One sample __ Fried"ick (1906).
Both Anoshin and Potap'yev (1966) and in magnetite than in the silicat~ minerals. Shcherbakov and Perezhogin (1964) show that Mantei and Brownlow accounted fc¥ the lower the gold in the quartz exceeds that in the gold content of magnetite, comparee- with other feldspars by a factor of 2. 7. Shcherbakov and minerals they analyzed, by pointing out that Perezhogin noted from the analyses of mono the structure of magnetite is relatively closed mineralic fractions of igneous rocks that the compared to the structures of biotite and horn average gold content decreases from magnetite blende and that "magnetite may bave formed and ferromagnesian silicates to feldspars. They before the silicates, at a time wh~n the con reported (table 3) the gold content of the centration of gold in the magma was fairly major rock-forming minerals as follows: low." quartz, 11 ppb (parts per billion); feldspa~r, Badalov (1965) examined tl'~ average 4 ppb; biotite, 4 ppb; muscovite, 3.8 ppb; amounts of gold, silver, selenium, and tellurium amphibole, 5.9 ppb; pyroxene, 16 ppb; olivine, in the disseminated copper-molybdonum depos 14 ppb; and magnetite, 48 ppb. its of the Almalyk district in t\e U.S.S.R. Mantei and Brownlow (1967) have made The sequence of the formation of the pre many neutron activation analyses of minerals dominate minem:ls in the ores was from earli from the Marysville quartz diorite stock (table est to llatest: magnetite, molybdenite, pyrite, 3). The diorite has an appreciably higher gold chalcopyrite, sphalerite, and galena. Pyrite is content than the average diorite, and most by far the most abundant mineral and carries of its component minerals have unusually high 3 ppm gold. Chalcopyrite is the :o;econd most gold contents. The reported gold contents in abundant mineral and was the chief "coneen crease from quartz and feldspar ( 65 ppb) trator" of gold; it contains 22 rpm. Native to biotite (76 ppb) and reach a maximum gold is common, and gold tellurid ~s are rare. in hornblende (100 ppb). The gold content N oddack and N oddack ( 1931) looked for of magnetite was found to be only 37 ppb, but did not detect gold in the for owing min in contrast to the findings of Shcherbakov erals: allanite, alvite (variety of zircon), an and Perezhogin ( 1964) who report more gold dalusite, 1aragonite, beryl, brewster~te, bronzite,
9 TABLE 3.-Analyses of gold in minerrals made since 1954
[Minerals containing higher amounts of gold are listed in table 1]
Gold Mineral and loeality (ppm) Remarks
Elements
Arsenolamprite, As Germany, Thuringia 5 Silver, 1 ppm. Spectographic an Fischer (1958-59). alysis. Iron, (Fe, Ni) U.S.S.R., Sikhote-Alin' ______1.15 One sample of meteorite. In troilite. ShcheJ·bakov and 0.067 ppm Au. Neutron activation Perczhogin analysis. (19fi4).
Snlftdes
Arsenopyrite, FeAsS U.S.S.R., Central Chukotki ______200 Samples from veins and ore miner Sidoro":r (1966). als. Germany, Thuringia .5 Silver, 15 ppm. Spectrographic an Fischer (1958-59). alysis. Chalcopyrite, CuFeSs U.S.S.R., Almalyk .22 Chalcopyrite is the chief "concen Badalc~r (1965) trator" but pyrite is ·the chief and Badalov and "carrier." Content in parts per Tere.khovich million of Pd, 0.21, Pt, 0.02, Ag, (196~). 0.02. Analyses by fire assay fol lowed by spectrographic. Germany, Thuringia .02 Pd, 0.2 ppm, Ag 10-3percent. Spec Fische~ (1958-59). trographic analysis. Cobaltite, CoAsS Germany, Thuringia 5 Silver, 20 ppm. Spectrographic an Do. alysis. Galena, PbS U.S.S.R: Central Chukotki ______5 Sidoro,. (1966). Almalyk ------13 Silver, 450 ppm. Pd, 0.032 ppm. Badalo"• and Analyses by fire assay followed Tere1rhovich by spectrographic. (1961i). Germany, Thuringia .01 Silver, 29-100 ppm. Spectrographic Fische1· (1958-59). analysis. Molybdenite, MoSs Germany, Thuringia .02 Content in parts per million of: Ru, Do. 0.03, Rh, 0.4, Pd, 0.6, Pt, 0.4, Ag. >lo-s percent. Pyrite, FeSt East Greenland ------·------ .016 Vincen-4: and U.S.S.R: Crocket (1960). Almalyk ------3 Content in parts per million of: Ag, Badalon ( 1965). 60, Se, 40, and Te, 16. Pyrite is the chief "carrier" but chalcopy rite is the chief "concentrator" of gold. Do 3.5 Silver, 36 ppm, Pt, 0.014 ppm. An Badalo"r and alyses by fire assay followed by Terel~hovich spectrographic. (196f). Central Chukotki ------10 Samples from veins and ore min Sidorov (1966). erals. Gennany, Thuringia ______.2 Silver, 5 ppm. Spectrographic an Fischer (1958-59). alysis.
10 TABLE 3.-Analyses of gold in minerals made since 1954-Continued
Gold Mineral and locality (ppm) Remarks :B~ference
Sulfid-<1ontinued
Pyrrhotite, Fet-xS East Greenland ______0.003 Analyses by neutron activation ___ _ Vince:-1t and Cro~ket (1960). U.S.S.R., Central Chukotki ______2 Samples from veins and ore min Sidorov (1966). erals. Sphalerite, (Zn, Fe) S U.S.S.R., Central Chukotki ______500 ______do Do. Stibnite, SlnSa U.S.S.R., Central Chukotki ______20 ______do ______Do. Germany, Thuringia ______.9 Silver, 2 ppm. Spectrographic an Fischer (1958-59). alysis. Troilite, FeS United States: Canyon Diablo, Ariz .10 One sample of meteorite. Analysis Baede.~ker (1967). by neutron activation. Sardis, Ga ------.23 One sample of meteorite found in Do. rocks of Miocene age. Analysis by neutron activation. U.S.S.R., Sikhote-Alin' ______.67 One sample of meteorite. The iron Shcherbakov and part of this meteorite contained Per~hogin 1.15 ppm Au. (19,~4). Ullmanite, NiSbS Germany, Thuringia 1 Silver, 10 ppm. SpectrogTaphic an FisCher (1958-59). alysis.
Sulfosalts
Tetrahedrite, Cu12Sb4S1a Germany, Thuringia 0.02 Silver, 20-100 ppm. Spectro- Do. graphic analysis.
Oxides
Magnetite, FeaO• United States, Helena, Mont ----- 0.037 Forty-four samples from the Manwi and Marysville quartz diorite stock, Brownlow 20 miles northwest of Helena, (19r,7). Mont. Fifty-one analyses made of these samples which ranged in gold from 0.003 to 0.329 ppm. Analyses by m~utron activation. U.S.S.R., Altai-Sayan folded belt (?) .048 Seven samples. Analyses by neu Shche... bakov and tron activation. Per?.zhogin (19r,4). Pyrolusite, Mn02 Germany, Thuringia Silver, 3 ppm. Spectrographic an FisCher (1958-59). alysis. Quartz, Si02 U.S.S.R.: Central Chukotki ______2 Samples from veins and ore miner- Sidorov (1966). als. Altai and Transbaikal ______.0008 Analyses by neutron activation. AnosUn and Potap'yev (1966). Altai-Sayan folded belt ( ?) ____ _ .011 Analysis by neutron activation. Shche... bakov and Nine samples. Per~hogin (19r,4).
11 TABLE 3.-Analyses of gold in mi:nerals made since 1951,-Continued
Gold Mineral and loeality (ppm) Remarks R'!ferenee
Oxides-Continued
Quartz and feldspar United States, Helena, Mont______0.065 TEm samples from the Marysville Mante~. and quartz diorite stock, 20 miles Brm..,Uow northweSt of Helena, Mont. (1967). Twelve analyses made of these samples which ranged in gold from 0.006 to 0.176 ppm. An alyses by neutron activation. Wad, Mn oxide Germany, ThUringia Silver, 5 ppm. Spectrographic an Fischer (1958-59). alysis.
Silicates
Feldspars, AI ,silicates with K, Na, and Ca U.S.S.R., Altai-Sayan folded belt (?) ------0.0040 Twenty-seven samples. Analyses by Shcher'-lakov and neutron activation. Perel;hogin (1964). Altai and Transbaikal ------.0003 Analysis by neutron activation. Anoshi"' and Pota:o'yev (1966). Microcline, KAISiaOs U.S.S.R., S. E. Altai ------.018 One sample from a migmatite. An- Shcherhakov and alysis by neutron activation. Pere?.hogin (19M). Amphiboles, hydrous silicates with chiefly Ca, Mg, Fe, AI, and N a U.S.S.R.: Altai-Sayan folded belt ( ?) •0059 Fourteen samples analyzed by Do• neutron activation method. Kuznetsk, Ala-Tau ------•077 Two samples analyzed by neutron Do. activation. Hornblende, CatNa(MgFeH)4 AI, 3 Fe + Ti) aSisOn (O,OH) 2 United States, Helena, Mont. ____ _ .100 Thirty-seven samples from the Mantei and Marysville quartz diorite stock, Brownlow 20 miles northwest of Helena, (1967). Mont. Forty-two analyses made of these samples which ranged in gold from 0.003 to 0.823 ppm. Analyses by neutron activation. Pyroxene, silicates of Ca, Mg, Fe, and others U.S.S.R., Altai-Sayan folded belt (?) ------.016 Eight samples analyzed by neutron Shcherbakov and activation. Perezhogin (1964). Tourmaline, complex silicate of B and AI U.S.S.R., Altai-Sayan folded belt (?) ------.012 Four samples analyzed by neutron Do. activation. Muscovite, KAlt (AI Sis) Oto(OH)J U.S.S.R., Altai-Sayan folded belt (?) ------.0038 Seven samples analyzed by neutron Do. activation.
12 TABLE 3.-Analyses of gold in minerals made since 1954-Continued
Gold :Mineral and locality (ppm) Remarks Refnrenee
Silicates-Continued
Biotite, K(Mg, Fe)s(AlS6) Oto(OH)I United States, Helena, Mont ______0.076 Forty-four samples from the Mantei and Marysville quartz diorite stock, Brownlow 20 miles northwest of Helena, (1967). Mont. Fifty-three analyses made of these samples which ranged in gold from 0.002 to 0.924 ppm. Analyses by neutron activation. U.S.S.R., Altai-Sayan folded belt (?) ------.0040 Eight samples analyzed by neutron Sheher't'f-tkov and activation. Perezhogin (1964). Altai ------•0091 Three samples from granite which Do. were analyzed by neutron acti vation. Olivine, (Mg,Fe)sSi04 U.S.S.R., Altai-Sayan folded belt (?) ------.014 Two samples analyzed by neutron Do. activation. Sphene, CaTiSiOs U.S.S.R., Altai-Sayan folded belt (?) ------.0039 Two samples analyzed by neutron Shcherl1.kov and activation. Perexhogin (1964). cristobalite, daubreelite (from meteorites), di Detected in 90-100 percent of opside, epidote, euclase, garnet, gersdorffite, the samples ------Ag, Cu, f'e harmotome, hauerite, heulandite, hornblende, Detected in 18.8-37.6 percent of the samples ------Ph, Ti, Al, Sb, Hg, kaolin, lepidolite, leucite, malachite, malacon, V, Bi, Mn, Si, As, molybandocker [ilsemannite], molybdosodalite, Sn muscovite, nepheline, olivine, orpiment, ortho Detected in 6.3-14.6 percent of clase, pyroxene, rhodochrosite, rutile, serpen the samples ______Mg, Ni, Ca, Zn, tine, stibnite, tantalite, thalenite, and thort Pd, Pt, Te Detected in 2.1-4.2 percent of veitite. The lower limit of detection of the the samples ______B, Co, C1·, Mo, Cd, analytical method they used seems to be about Rh, Sr, W, Zr 10 ppb. Other specimens of some of these It is probable that not all the elements in the forego minerals analyzed by neutron activation meth ing list were looked for by most analysts. ods also show less than 10 ppb Au (table 3). Warren and Thompson (1944) studied the Platinum exceeds gold in meteorites, as well composition of 66 samples of native Jr">ld, about as in metasilicate minerals and orthosilicate 75 percent of which originated ir Canada. minerals. All samples contained silver, copper~ and iron. The number of occurrences of the varous other COMPOSITION AND THE FINENESS OF GOLD elements in the gold were: titanium. 52~ mer Samples of native gold from 48 places cury, 42: manganese, 40~ lead, 37; vanadium, throughout the world have been analyzed for 28: tin, 22: antimony, 21; bismuth, 19r arsenic, selected elements (Gay, 1963). The frequency 17~ zinc, 1&, cadmium, 14, tellurium. 8: plati of occurrence of 30 elements detected (in order num, 3t and palladium, 2. Silver w".c; usually of frequency) is as follows: present in amounts exceeding 0.5 p~rcent and
13 copper was usually present in amounts from that this seemed to indicate that the deposits 0.1 percent to 0.5 percent. The remaining ele were formed by diffusion of gold and silver ments, when present in the gold, were usually through the cou.ntry rock. For instance, in in amo'Jnts of less than 1 percent. the Yellowknife district of Cans da, gold -in deposits in greenstone has a gold~silver ratio Wise (1964), in a study of binary alloys of 5:1 ( = fineness 833), whernas gold in of gold, gives the various maximum high-tem quartz lenses in sedimentary rocks has a ratio perature solid solubilities of elements in gold of 3.5:1 ( = fineness 778). Ward observed as follows: that gold in some ore bodies in '\\~estern Aus 100 percent ______Ag, Cu, Ni, Pd, Pt tralia that are genetically relatr1 to albite 46 percent _------Fe porphyry intrusives has a gold to silver ratio 21.5---19 percent ______Cd, Cr, Hg greater than 9:1 ( = fineness 9(1). Lincoln 13 percent ------Zn 10.9-7.7 percent ______Mn, Ta, Co, In noted that the fineness of gold i~ higher in 5.2-1.2 percent ______V, Ga, Sn, Mg, AI, silicic igneous rocks than in maf~ varieties; Ti, Ge gold in silicic igneous rocks aver? ~es 979 in <1 percent ------As. Bi, Ca, Mo, Pb, fineness, that in intermediate typ~s 451, and Pr, Rh, Sb, Th, that in mafic types 245. Tl, U, and per haps others. Native gold at the surface and in the oxidized The fineness of gold, and especially its rela zone of a mineral deposit is usuall:.. finer than tion to the genesis of gold denosits. has been is the native gold in the unoxidizei ore (Don, studied by numerous workers (Gay, 1963; Sun 1898; Fisher, 1945; Colin, 1946; MacGregor, dell, 1936; Mertie, 1940). Fineness refers to 1928; Mackay, 1944; Mills, 1954. and Gay, the ratio of gold to the sum of the gold plus 1963). Below the oxidized zone, hc~~ever, gold fineness seems to be largely ind~pendent of the silver in the naturally occurring alloys depth (Gay, 1963). A small decr~ase in the and is defined as 1,000 times Au/(Au+Ag). fineness of gold with depth in the. Lily mine, Me:rtie (1940) noted that pure gold has not Republic of South Africa, is reported by An been found in nature, but that gold is always haeusser (1966) and shown in 1able 4. On alloyed with silver and a small amount of the other hand, average gold fine~ess in the the base metals such as iro.n and copper. The Zwartkopje shoot in the Sheba mine, Repub purest gold reported by Mertie was from the lic of South Africa, increases with depth from Great Boulder mine, in the Kalgoorlie district the 14 level (about 910 fine) to 1he 26 level of Western Australia; it was 999.1 fine. Mertie (about 950 fine) within a vertical distance of about 550 feet (Gay, 1964). concluded that fineness is rarely less than 600
and is generally never less than 400, although TABLE 4.-Variations in fineness of gold with depth, Lincoln (1911) reported a fineness of 246 for Lily Mine, Transvaal, South Africa
· silver-gold alloys in some mafic igneous rocks. [After Anhaeusser, 1966] The color of gold in polished section is an Depth in feet index of its fineness, according to Eales (1961). below 2,600-foot Nearly pure gold has a golden color with a datum Gold Silv·~r Level plane (percent) (percent·) Fineness ruby tint. With increasing amounts of silver, 70-foot ______. _ ---- 200 91.50 8.50 915 1 ----- ·------·------260 91.15 8.85 911.5 the color changes to yellow and eventually 1% _.. ------340 90."8 9 72 903 becomes ~ pale silvery yellow color as in elec 2------. 420 89.04 10.96 890 trum. Others have noted color differences in gold due to variations in fineness (Mather, Gold fineness was noted by Gay (1963) to vary from east to west in some Witwatersrand 1937; Russell, 1929; Edwards, 1958). deposits as follows: 865.8, 884.0, 870.6, 926.0, Boyle (1960), Ward (1958), and Lincoln 912.0, 924.0, and 970.0. Sharwood (1911) re (1911) have commented on the fineness of ports some lateral variation in fineness of bul gold in different country rocks. Boyle thought lion from mines in the Lead district, South that the fineness of gold in lode deposits re Dakota; as shown in table 5, the range in flected the nature of the country rock and fineness is small.
14 TABLE 5.-Fineness, in percent, of mill bullion prior to the gold. Shcherbina (1956) explains that the 1882 at the Homestake mine, South Dakota high ratio of silver to gold, 37J\ (Mason, [Sharwood. 1911] 1952) in sea waters, compared to only about Base Mine Gold Silver metal' Fineness 10 (Vinogradov, 1956) for the lith9sphere as a whole, is an indication of the gre~.ter mobil Homestake ______82.0 17.0 1.0 828 Highland ______83.0 15.5 1.5 843 ity of silver. Terra ______82.5 16.0 1.5 838 Deadwood ______------85.0 14.0 1.0 859 Mertie (1940) says that in sotro. Alaskan 17.0 1.0 828 De Smet ------82.0 paystreaks the fineness of gold incre.q,ses down Lateral variation in fineness is shown by stream from its source, but in others the fine analyses of the bullion from nine representa ness changes either erratically or not at all. tive mines in Gilpin County, Colo. (Collins, He cites an Alaskan placer gold d~posit that 1902). During the period 1870 to 1880, the was derived from lodes in Tertiary quartz fineness ranged from mine to mine from 753 monzonite. The source lodes were being actively to 897, and during the period 1880 to 1890, mined around 1940, and informat~0n on the from 716 to 894. The average fineness of all fineness of both lode and placer gold indi the bullion from these mines changed little cates that the fineness does not increase pro during the two periods; it was 799 for the gressively downstream. first and 789 for the second. Fineness varies not only from gr8.in to grain Eales (1961) studied the silver content of but also w.jthin graillls (Gay. 1963). Some gold from four hydrothermal deposits in grains are finer in the center than on the Southern Rhodesia. Gold that mineragraphic surface (Head, 1935), although Er.les (1961) studies show to have crystallized early, and has noted the reverse. Gold extrac~ed by Mc that is enclosed in chalcopyrite and sphalerite, Connell (1907) from the outer surface of a contains more silver than does gold that crys nugget assayed 60-70 parts per tho~lsand finer tallized later. than gold from the inside of the rugget, and The fineness of gold varies directly with his findings have been cited as evidence that particle size in some deposits and inversely surface waters dissolve an appreciable amount with particle size in others (Gay, 1963). of silver from alluvial gold. However, the dif ference could have been due to the original For ore deposits in general, the fineness character of the primary lode gold or to sur of the contained gold increases as the grade of ficial enrichment of the gold in the zone of ore increases; (Eales, 1961; Lawn, 1924; Mac- oxidation before it was freed (Mertie, 1940). Gregor, 1928; and Mackay, 1944). Very fine grained placer gold is u~ually finer Fisher ( 1950) concluded that fineness used than the coarse gold (Hite, 193~; Sundell, with other criteria furnishes a sensitive and 1936; Fisher, 1945; and Colin, 1~46). How reliable guide to the relative temperature of ever, Mertie (1940) reports that in any one ore formation, at least within the epithermal paystreak, and at any o.ne place in the pay and the upper part of the mesothermal range streak, the reverse is usually true. of temperatures. The fineness of epithermal gold is from 500 to 700. Near the bottom of the epithermal zone (corresponding to the REFERENCES CITED leptothermal zone of Graton, 1933), the fine Anhaeusser, C. R., 1966, Supergene goH enrichment ness is about 700 and may be as much as in the Barberton Mountain Land wth particular 800. The fineness of mesothermal gold varies reference to the Lily Mine: Witwatersrand Univ. from 750 to 900, with 850-870 being common. Econ. Geology Research Unit lnf. Circ. 29, 16 p. The fineness of hypothermal gold is always Anoshin, G. N., and Potap'yev, V. V., 1966, Gold in granites of the Kolyvan' (Altay) ard Khangilay greater than 800. Fineness of 900 or more Shilinskiy (Transbaikalia) massifs (according to results from oxidation under conditions fav radioactivation analysis data): Geokhimiya, no. 9, oring the removal of silver. p. 1070-1074 (in Russian). Translation in Geo chemistry Internat., 1966, v. 3, no. 5, f· 850-854. Gay (1963) observed that commonly the Badalov, S. T., 1965, On the role of predominant fineness of placer gold increases downstream components in the geochemistry of minor and rare from its so·Jrce. This increase is explained elements of ore deposits: Geochemistry Internat., by leaching of the silver and redeposition of v.2, no. 5,p.857-860.
15 Badalov, S. T., and Terekhovich, S. L., 1966, Geo de leur stabilite: Mineralium Deposita, v. 1, p. chemistry of elements of the Pt group in the 259-268. Almalk ore region: Akad. N auk SSSR Doklady, Graton, L. C., 1933, The depth-zones in or~ deposition: v. 168, p. 1397-1399 (in Russian). Econ Geology, v. 28, p. 513-555. Baedecker, P. A., 1967, The distribution of gold and Head, R. E., 1935, Form and occurrence of gold in iridium in meteoritic and terrestrial materials: pyrite-coated gold: Canadian Minir~ Jour., v. U.S. Atomic Energy Comm. [Pub.] OR0-2670- 56, (II), p. 517-521. 17, -and Ph. D. thesis, Kentucky Univ., 110 p. Hegemann, Friedrich, and Leybold, Chr., 1954, Boyle," R. W., 1960, The geology, geochemistry and Eine Methode zur quantitative sp~ktrochemis origin of the gold deposits of the Yellowknife chen Analyse von Pyrite: Zeitschr. Erzbergbau district: Canada Geol. Survey Mem. 310, 193 p. u. Metallhiittenwesen, v. 7, p. 108-113. Cloke, P. L., and Kelly, W. C., 1964, Solubility of Helgeson, H. C., and Garrels, R. M., 1968, Hydro gold under inorganic supergene conditions : Econ. thermal transport and deposition of gold: Econ. Geology, v. 59, p. 25,9-270. Geology, v. 63, p. 622-635. Colin, L. L., 1946, Gold fineness in relation to geology; Hite, T. H., 1933, Fine gold and platinum of Snake considerations of the Macequece field [Mozam River, Idaho: Econ Geology, v. 28, p, 256-265. bique]: S.outh Africa Mining and Eng. Jour., v. Krauskopf, K. B., 1951, The solubility of gold: Econ. 57, pt. I, p. 279-283. Geology, v. 46, p. 858-870. Collins, G. E., 1902, The relative distribution of gold and silver values in the ores of Gilpin County, Lawn, J. G. E., 1924, Presidential add1·~ss on the Colorado: Inst. Mining and Metallurgy Trans. subject of silver in Witwatersrand ores: Geol. (London) v. 12, p. 480-499. Soc. South Africa Proc., v. 27, p. 19-31. Don, J. R., 1898, The genesis of certain auriferous Lincoln, R. C., 1911, Certain natural ass'leiations of lodes: Am. Inst. •Mining Engineers Trans., v. 27, gold: Econ. Geology, v. 6, p. 247-302. 564-668. Liversidge, A., 1897, Presence of gold in natural Eales, H. V., 1961, Fineness of gold in some Southern saline deposits and marine plants: ~Tour. Chern. Rhodesian gold mines: Inst. Mining and Metal Soc., v. 71, p. 298-299. lurgy Trans., Bull. no. 660, v. 71, p. 49-73. McConnell, R. G., 1907, Report on the gold values in the Klondike high-level gravels: Cz.nada Geol. Edwards, A. B., 1958, The mineral composition of the Maude and Yellow Girl gold ore, Glen Wills, Survey, no. 979, 134 p. Victoria: F. L. Stillwell Anniversary Volume MacGregor, A. M., 1928, The geology of the country Melbourne, Australasian Inst. Mining and Metal around the Lonely Mine, Bubi Dis4:rict: Geol. lurgy p. 105-132. Survey Southern Rhodesia Bull., no. 11, 96 p. Fischer, Karl-Wilhelm, 1958-59, Zur Geochemie der Mackay, R. A. C., 1944, Purity of nativ~ gold as a Edelmetalle. Spektralanalytische Untersuchungen criterion for secondary enrichme.nt: Econ. and Thiiringer Gesteinen und Mineralien: Wiss. Geology, v. 39, p. 56-68. Zeitschr. Hochschule f. Architekur u. Bauwesen Mantei, E. J., and Brownlow, A. H., 1967, Varia Weimar, v. 6, no. 2, p. 85-91. tiQn in gold content of minerals of the Marys Fisher, N. H., 1945, The fineness of gold, with special ville quartz diorite stock, Montana: Geoehim. et reference to the Morobe gold field: Econ. Geology, Cosmochim. Acta, v. 31, no. 2, p. 225-23L v. 40, p. 449-495 and 537-563. Mason, Brian, 1952, Principles of geocheirtstry: New 1950, Application of gold· fineness to the York, John Wiley and Sons, 276 p. search for ore: Australasian Inst. Mining and Mather, W. B., 1937, Geology and par,,genesis of Metallurgy Proc. 156-157, p. 185-190. gold ores of the Howey mine, Red Lal·~, Ontario: Friedrick, K., 1906, Untersuchungen iiber den Goldge. Econ. Geology, v. 32, p. 131-153. halt von Gebirgsproben and Solen deutscher Mertie, J. B., Jr., 1940, Placer gold in Ala~ka: Wash Salzlagerstatten: Metallurgie, v. 3, no. 2, p. 627- ington Acad. Sci. Jour., v. 30, p. 93-124. 630. Mills, J. W., 19'54. Vertical zoning at the O'Brien Gay, N. C., 1963, A review of the geochemical char gold mine, Kewagama, Quebec: Econ. Geology, v. acteristics of gold in ore deposits: Witwatersrand 49, p. 423-430. Univ. Econ. Geology Research Unit Inf. Circ. 12, Minguzzi, Carlo, 1947, Dosatura spettro:n-afica dell 70p. oro in piriti italiane: Soc. Toscana Sci. Nat. Atti., 1964, The composition of gold from the Mem., v. 54, p. 210-243. Barberton mountain land: Witwatersrand Univ. Noddack, Ida, and Noddack, Walter, 1931. Die Geo Econ. Geology Research Unit Inf. Circ. 19, 53 p. chemie des Rheniums: Zeitschr. Phys. Chemie, v. Goldschmidt, V. M., and Peters, Cl., 1932, Zur 154A, p. 207-244. Geochemie des Edelmetalle: Gesell. Wiss. Got Ottemann, J., and Augustithis, S. S., 1967, ~chemistry tingen, Nachr., Math-Phys. Kl. no. 4, p. 377-401. and origin of "platinum-nuggets" in lateritic Goni, J ., Guillemin, C., and Sarcia, C., 1967, Geo covers from ultrabasic rocks and b~rbirites of chemie de l'or exogime. Etude experimentale de W. Ethiopia: Mineralium Deposita, v. 1, p. 269- la formation des dispersions colloidales d'or et 277.
16 Palache, Charles, Berman, Harry, and Frondel, Shcherbakov, Yu. G., and Perezhogin, G. A., 1964, Clifford, 1944, Dana's System of Mineralogy: 7th Geochemistry of gold: Geochemistry Internat., ed., New York, John Wiley and Sons, v. 1, 834 p. no. 3, p. 489-496. Ramdohr, Paul, 1967, The wide-spread paragenesis of Shcherbina, V. V., 1956, The geochemical significance ore minerals originating during serpentinization: of the quantitative silver/gold ratio: Geokhimiya, Geologiya Rudnykh Mestorozhdenii, no. 2, p. 32- no. 3, p. 65-83 (in Russian). 43 (in Russian). Sidorov, A. A., 1966, Gold-silver mine¥alization of Ringwood, A. E., 1955, The principles governing Central Chukotki: Akad. N auk SSfR Magadan. trace element distribution during magmatic Severo-Vostoch. kompleks. N auchno.-Issled. Inst. Trudy, vyp. 14, 146 p. (in Russian). crystallization: Geochim. et Cosmochim. Acta, v. 7,p. 189-202,242-254. Sundell, I. G., 1936, Fineness and co"'llposition of alluvial gold from the Ivalojoki, Finnish Lap Russell, A., 1929, On the occurrence of native land: Comm. Geol. Finlande, Bull. no. 115, p. gold at Hope's Nose, Torquay, Devonshire: 155-1.60. Mineralog. Mag., v. 22, p. 159-162. Terziev, G., 1966, Kost.ovite, a gold-coiJper telluride Schneiderhohn, H., 1929, The mineragraphy and spec from Bulgaria: Am. ;Mineralogist, v. 51, p. 29-36. trography of the sulfide platinum ores of the Vincent, E. A., and Crocket, J. H., 1961), Studies on Bushveld complex, chap. XVII, p. 206-246, in the geochemistry of gold. I. The distribution of Wagner, P. A., The platinum deposits and mines gold in rocks and minerals of the Skaergaard of South Africa: Edinburgh and London, Oliver intrusion, East Greenland: Geochim. et Cosmo and Boyd. chim. Acta, v. 18, p. 130-142. Schneiderhohn, H., and Moritz, H., 1931, Spektro Vinogradov, A. P., 1956, Regularity of distribution of chemical elements in the earth'f crust: Geo graphische Untersuchungen iiber die Verteilung khimiya, translation, no. 1, p. 1-43. der Platinmetalle in den Mineralien der siida frikanischen Plantinlagerstiitten: Festschr. d. Ward, H. J., 1958, Albite porphyries as a guide to gold ore: Econ. Geology, v. 53, p. 754-756. Platinschmelze G. Siebert, Hanau, p. 257-287. Warren, H. V., and Thompson, R. M., 1944, Minor Schwartz, G. M., 1944, Host minerals of native gold: elements in gold: Econ. Geology, v. 39, p. 457- Econ. Geology v. 39, p. 371-411. 471. Sharwood, W. T., 1911, Analyses of rocks and Wise, E. M., 1964, Gold: recovery, properties, and minerals from Homestake mine, Lead, South applications: New York, D. Van }ITostrand, Co., Dakota: Econ. Geology, v. 6, p. 729-789. Inc., 367 p.
17