174 A4/A3 THE GEOCHEMISTRY OF ANTIMONY AND ITS USE AS AN INDICATOR ELEMENT IN GEOCHEMICAL PROSPECfING SILVER DEPOSITS - AN OVERVIEW OF THEIR TYPES, GE<X:HEMISTRY, PRODUCTION, AND ORIGIN. GOLD DEPOSITS - AN OVERVIEW OF THEIR TYPES, GEOCHEMISTRY, PROOUCTION, AND ORIGIN PROSPECTING FOR GOLD AND SILVER OEPOSITS SILVER DEPOSITS AND GECX:HEMICAL METHODS OF THEIR DISCOVERY GOLD DEPOSITS AND GEOCHEMICAL METHODS OF THEIR DISCOVERy GeochemicaI methods for the discovery of blind mineral deposits R.W. BOYLE Georogical Survey of Canada Ottawa Journal of Geochemical Exploration, 20 (1984) 223-302 223 Elsevier Science Publishers B. V., Amsterdam - Printed in The Netherlands THE GEOCHEMISTRY OF ANTIMONY AND ITS USE AS AN INDICATOR ELEMENT IN GEOCHEMICAL PROSPECfING R.W. BOYLE and I.R. JONASSON Geological Survev of Canada, 601 Booth Street, Ottawa, Ont. K1A OE8 (Canada) (Received October 31, 1983) ABSTRACT Boyle, R.W. and Jonasson, I.R., 1984. The geochemistry of antimony and its use as an indicator element in geochemical prospecting. J. Geochem. Explor., 20: 223-302. The geochemistry of antimony is reviewed, and the use of the element as an indicator in geochemical prospeoting for various types of mineral deposits is outlined. Antimony is widely diffused in many types of mineral deposits, particularly those containing sulphides and sulphosalts. In these and other deposits, antimony commonly accompanies Cu, Ag, Au, Zn, Cd, Hg, Ba, U, Sn, Pb, P, As, Bi, S, Se, Te, Nb, Ta, Mo, W, Fe, Ni, Co , and Pt metals. Under most conditions antimony is a suitable indicator of deposits of these elements, being particularly useful in geochemical surveys utilizing primary halos in rocks, and secondary halos and trains in soils and glacial materials, stream and lake sediments, natural waters, and to a limited degree vegetation. Some of the natural antimony compounds (e.g. stibine, dimethylstibine) are volatile, but methods utilizing gaseous antimony halos for geochemical prospecting have not yet been devel­ oped. INTRODUCTION Antimony is an ancient element and is mentioned in the Old Testament (II Kings, 9, 30), "and she painted her face (with stibium)". The reference is to the use of stibnite as a cosmetic for darkening the eyes. Pliny Secundus called the element stibium, and in a latin translation of Geber, the alchemist, it is termed antimonium. The element was prepared and its compounds described by Basil Valentine (probably Tholde) in his treatise "The Triumphal Chariot of Antimony" written in the 15th century. Antimony is widely diffused in nature and is concentrated in many types of mineral deposits, particularly those containing sulphides and sulphosalts. It accompanies many elements in their deposits including Cu, Ag, Au, Zn, Cd, Hg, Ba, U, Sn, Pb, P, As, Bi, S, Se, Te, Nb, Ta, Mo, W, Fe, Ni, Co, and Pt metals. Antimony is, therefore, an ideal indicator in geochemical prospecting surveys for some twenty elements of commercial importance. In preparing this outline of the geochemistry of antimony we have con­ sulted most of the literature available on the element up to the end of 1982. 0375-6742/84/$03.00 © 1984 Elsevie r Science Pu hlisbers B.V. 224 This we have supplemented with our own data and research on the geochem­ istry of antimony extending over a period of same thirty years. During the compilation of the tables on the normal or background abundance of anti­ mony in the various earth materials we encountered considerable difficulty in deciding which analytical data in the literature should be used in our calculations because of the different analytical procedures employed, rock nomenclature, possible presence of antimony mineralization, and so on. These problems are familiar to all geochemists who attempt to calculate normal or background abundance figures. We have been selective in our compilation, utilizing only those data which in our opinion have been ob­ tained by reliable modem analytical procedures on earth materials which seemed to us from the descriptions of the samples to be well removed from the effects of antimony mineralization. Admittedly, this is a subjective pro­ cedure, and we would stress the fact that our abundance figures are only estimates at best. All of our data sources are given in the Selected Bibliog­ raphy at the end of the paper. GENERAL GEOCHEMISTRY AND MINERALOGY Antimony is the fourth member of Group VA of the periodic system, which also includes nitrogen, phosphorus, arsenic, and bismuth. In some of its chemical reactions antimony behaves much like arsenic and bismuth. In nature three oxidation states are possible for the element - the metallic or covalent (O) state, and the (III) and (V) states. The metallic state is not uncommon for the element in certain types of mineral deposits. The (III) and (V) states are common in a variety of complex minerals and in dissolved salts in natural waters. The (III) state is also represented in the gaseous compound SbH3 (stibine) which may occur under certain natural conditions. Because of the multiple oxidation states of the element and the tendency to form soluble complexes and complex compounds, the geochemistry ,of antimony is intricate and not weIl characterized. A generalized cycle of anti­ mony interconversions in nature is shown in Fig. 1. The elements most frequently associated with antimony in nature are arsenic and sulphur. Antimony has two stable isotopes in nature, the conventional abundances being as follows (Lederer and Shirley, 1978): 121Sb 57.3% 123Sb 42.7% No authenticated differences in the isotopic composition of antimony have yet been found in nature. Radioactive an timony isotopes are commonly noted in the atmosphere after thermonuclear explosions. The half life of most of these isotopes is short (e.g. 124Sb - 60.2 d; 125 Sb - 2.71 y). Native antimony is relatively common in certain types of mineral deposits despite the fact that the element has a marked chalcophile character forming sulphides and a great variety of sulphosalts, particularly with the metals Cu, Ag, Zn, Hg, Pb, and Fe. The most common of these sulphosalts is tetrahedrite­ ... 225 IEROVALENT Sb eecurs ,n nature ImmobIle IOlms as nahve .nhmony Immobile lorms. in Ollide. sulphlde. sulphlde-olllde and In certa," in oxide. sulphlde. and and ",alIOUS antimonites. In metall.c alloys vaflous complex anlimonates and antimon.des hydlous manganese Olit ide (Ich in hydrous manganese oxide (Immobile 101ms) gels: In ilon-manganese tlch rich gels: ,n Ilon-manganese olganlc maltel such as peat. tlCh organlc matter such as gy",a. humus. ,n plants and Sb(O) peat, gyttja. humus. animals In planIs and animals. ........ <,O,-,,~ \~ " ('I,,~o: <.9 "C' \~ ,\~. O O.., \~o. \ "2­ ~-;o \../ \'" \ "O \ O PENTAVALENT Sb ~ malnlyantonic \ \ \ (j\' torms preva.' \"2- V~ ~ I ~ e g. SbO. 3­ IJ'_ (1) and Ihioanlimonales \~ I Oxidation in SOI_u-:-tio_n..,...o_,__.-_<.9-Y{b (V) by action ofbacte,ia Mobtle larms. MobIle larms as ax 'des and sulph,des In as oxide conoids or sols. In sols and collaIdai gels. hydrous «on-manqanese oxroe anllmonue (01 lhlo.nt,monlle) couo.os and gels. as orqamc scsoens.oos. soluble species enerates or In gels: as mineral and acsorbed ions: in organic partieulates. in suspensrons or cbeiates and couo-cs: and as dust: as anlimonyl. antimorrate posstbly as volalile hydlides or Ihioanl,monale rons (and or alkyl hydlides: as complex hydrolyles) in sotuuon: as rons In sotu.ion. In dust: In complex lons 01 potymerrc hydrocarbons lons in solvhon : in hydrocarbons Fig. 1. Cycle of antimony interconversions in nature. tennantite. Antimony forms oxides and complex oxides in nature, and there are a large number of natural antimonites and antimonates and other corn­ plex oxygen-salts of the element. The biophile character of antimony is manifest by its presence, usually in small amounts, in a variety of living organisms and their fossil equivalents. The principal antimony minerals are given in Table r. Only the most com­ mon antimonites and antimonates are given. The principal antimony miner­ als in endogene (hypogene) deposits are native an timony, stibnite, tetra­ hedrite, jamesonite, boulangerite, and pyrargyrite. The other sulphosalts of the element are relatively rare. The common supergene antimony minerals, formed as a result of oxidation of the hypogene sulphides, sulphosalts, etc., are senarmontite, stibiconite, kermesite, and bindheimite. Antimony is found as traces and minor quantities in many of the native elements, in practicallyall the common sulphides, and in a great variety of secondary oxidation produets, particularly in sulphates, arsenates, etc. The element is also a trace or minor constituent in a number of complex niobates and tantalates. The principal carriers of antimony in rocks and in many types of mineral deposits are arsenopyrite and pyrite. The latter mineral may contain up to 100 ppm or more Sb, the element being apparently present in lattice sites 226 TABLE I Antimony minerals Native dement. ond in termetallic comp ounds: AnUmony Sb Al1emontite SbAs + ~ or Sb SUb~en Sb~ Paradocra.site Sb1(Sb,As)1 Sulpnide«, an tim onides, arseniäes, teliurides, etc. Stibnite Sb2S, Geversite PtSb1 Metastibnite Sb2S, lruizwaite Pt(Bi,Sb), Wakabayashilite (As,Sb).. Sil SUbiopalladinite Pd,Sb2 Cuprostibite Cu 2(Sb,TI) Genkinite (Pt,Pd)..Sb, Horsfordite CusSb Isomertieite Pdl1Sb2~1 Allargentum Agl~Sbx Mertieite - I Pd1•(Sb,As).. Dyscrasite Ag,Sb Mertieite - II Pd.(Sb,As), Stistaite SnSb Arsenopalladinite Pd.(As.Sb), Breithauptite NiSb Testibiopalladite Pd(Sb.Bi)Te Sudburyite (Pd,Ni)Sb Hexatestibiopanickelite