美国内华达卡林金矿之含金FeS_2微晶中不可见金的TEM研究和地球化学模型_英文

美国内华达卡林金矿之含金FeS_2微晶中不可见金的TEM研究和地球化学模型_英文 2000 年 12 月 Geolo gical J o ur nal of Chi na U niver sities Dec , 2000 () 文章编号 :1006Ο7493 200003Ο0523Ο09 美国内华达卡林金矿之含金 Fe S微晶中 2 不可见金的 T EM 研究和地球化学模型 Investigation of Invisible Au in Au2bearing FeS 2Microcrystal s f rom Carl in Gol d Ore Deposit , Neva da , USA :TEM Study and Geochemical Model ing 徐惠芳 XU Hui2f ang () querque ,NM 87131美国新墨西哥大学地球与行星科学系 ,Albu Depart ment of Ea rt h an d Pl anet a ry S ciences , T he U ni versi t y of N ew M ex ico. A l buquerque , N ew M ex ico 87131 , U . S . A . 摘 要 : 透射电子显微术的研究明 ,美国内华达州卡林金矿中环绕黄铁矿大晶体的 Fe 的硫化物 微晶乃是白铁矿 。该白铁矿含 Au 和 As ,并在其中有纳米尺度的似带状区 。相对于邻区而言 ,似带 状区相对富 As 。因而提出 :似带状区还相对富晶格金 。根据所得出的方解石中三价阳离子的分配 3 + () 系数方程认为 ,Au阳离子是在白铁矿的非平衡 快速结晶作用期间 ,从白铁矿 - 溶液界面上被3 + ( ) 结合到细粒白铁矿中去的 。Au在白铁矿中的配分是由非平衡分布系数 K’所控制的 。然而 , d 3 + 3 + ( ) () 由于 Au的平衡分配系数 K小 ,故通过平衡 缓慢结晶作用形成的黄铁矿并不将 Au结合到 d 晶体中去 。早期形成的细粒晶体的再结晶作用则将把 R EE 和 Au 从晶体中迁移走 。相对于正常 3 + + 的白铁矿结构而言 ,较大的 Au和 Au 阳离子结合进入到白铁矿晶格中 ,可引起局部的结构畸 变 ,从而表现为似带状的特征 。 ( ) 关 键 词 : 不可见金 ; 白铁矿 ; 黄铁矿 ; 高分辨透射电子显微术 HR T EM; 非平衡分配系数 中图分类号 : P57512 文献标识码 : A Abstract : Transmissio n elect ro n microscop y st udy indicates t hat microcrystalline Fe2sulfide crystals around large p yrite crystals f ro m Carlin mine of Nevada are marcasite. The marcasite co ntains Au and As. There are band2li ke feat ures in t he marcasite. These band2li ke areas are relatively rich in As wit h respect to t he neighboring areas. It is p roposed t hat t he band2li ke areas are also relatively rich in lat tice2 bound Au. According to t he obtained equatio n for dist ributio n coefficient s of t rivalent catio ns in calcite , 3 + it is p roposed t hat catio nic Auwere incorporated into t he fine grain marcasite at t he marcasite - solu2 3 + () tio n interface during no n2equilibrium fastcrystallizatio n of t he marcasite. The partitio ning of Auin ’) ( t he marcasite is co nt rolled by no n2equilibrium dist ributio n coefficient K. However , p yrite formedd 3 + ( ) t hrough equilibrium slowcrystallizatio n will not incorporate Auinto t he crystal , because of it s low 收稿日期 : 2000201212 ; 修订日期 :2000202226 ( ) 基金项目 :中国国家自然科学基金资助项目 No . 49928201;美国 NSF 、NASA 和新墨西哥州资助课 3 + ) ( equilibrium dist ributio n coefficient Kfor Au. Recrystallizatio n of early2formed fine grain crystals d 3 + + will remove R EE and Au f ro m t he crystals. Incorporatio n of larger catio ns of Auand Au may result in local st ruct ural distortio n wit h respect to normal marcasite st ruct ure , and shows t he form of t he band2 li ke feat ure. Key words : Invisible gold , marcasite , p yrite , high2resolutio n , t ransmissio n elet ro n microscop y ( ) HR T EM, no n2equilibrium dist ributio n coefficient 1 Int ro ductio n Because of t he eco no mic impo rtance of gold metal , much effo rt has been directed to t heir dis2 1 () t ributio n in o res and minerals . Gold no r mally occurs in o res in t he part s per millio n pp mco ncent ratio n range , and so it is of paramo unt impo rtance to maximize recovery. Therefo re , knowledge of t heir dist ributio n in t he vario us mineral p hases is impo rtant . However , o ur p rimary interest , w hich is mo re scientific t han eco no mic , is t he means by w hich t he gold element dist ributed in minerals. Gold in grains smaller t han t hat can be o bserved by standard op tical techniques is co mmo nly called“invisible”o r“lat tice2bo und”gold. It s occurrence in sulfide o res is of significant technoΟ lo gical impo rtance because it is usually not amenable to recovery by cyanidatio n . It is t herefo re ( ) impo rtant to deter mine t he relative amo unt s and dist ributio n of bot h native elementaland real invisible gold in sulfide minerals. Recent T EM st udies show nano meter size gold particles associated wit h quartz , illite , and 2 ,4 microf ract ures. However , we need to know t he chemical states of real invisible gold in t he lat tice st ruct ure of sulfides. Ult rafine milling might make t he nano meter size colloidal particles amenable to cyanidatio n , but not t he lat tice2bo und gold. It was p ropo sed t hat t hese nano meter size gold particles result f ro m re2mo bilizatio n of p rimary real invisible Au in relative o xidizing 2 co nditio n. It is also p ropo sed t hat surf ace so rp tio n induced reductio n of Au2bearing solutio n can 5 also result in fo r matio n of nano meter size Au particles o n sulfide mineral surf aces. The occurrence and dist ributio n of “invisible”Au in p yrite and arsenop yrite has been t he 6 ,11 subject of numero us investigatio ns . Au in solid solutio n in t he arsenop yrite st ruct ure has ( ) ( ) been po st ulated by Wagner et al . 1986 , Jo han et al . 1989 , and Wu & Delbove 10 ,12 () 1989. However , t he st ruct ural and chemical states of t he real invisible Au is still notclear. In t his paper , t he p reliminary high2resolutio n T EM result s of fine grain crystals of Au2bearing marcasite are described. 2 Sa mple and Experi ment al Met ho d ( ) The sample of p rimary Au o re is f ro m Carlin mine of Nevada U . S. A . . The sample () ( ) co ntains large Au2poo rp yrite crystals surro unded by fine grain relatively Au2richFe2sulfide crystals. The fine grain Fe2sulfide crystals are relatively rich in Au. The fine grain crystals were co nsidered as p yrite befo re . The result s f ro m t his st udy indicate t hat t hey are marcasite . Ot her coexisting minerals are illite and microcrystalline quartz. Do uble2side polished pet rograp hic t hin sectio ns were p repared f ro m t he collected sample . The areas co ntaining t he fine grain Fe2sulfide crystals were selected fo r T EM st udy. The selected samples were mo unted o n Cu grids , and t hen io n milled using a cooling stage . The io n2milled specimens were coated wit h a t hin carbo n layer . All t he T EM and EDS data were carried o ut at t he Transmissio n Elect ro n Micro scop y L abo rato ry of t he U niversit y of New Mexico using a high resolutio n T EM and associated EDS system. 3 T EM Result s ( ) Selected area elect ro n diff ractio n SA EDpat ter n f ro m t he fine grain crystals indicates t hat ( ) t he Fe2sulfide crystals are marcasite Fig. 1, instead of p yrite . The crystals co ntain As. High2 ( ) resolutio n t ransmissio n elect ro n micro scop y HR T EMst udy show s t hat t here are microcrystals ( ) have nano meter size band2like zo nes in t he As2 and Au2bearing marcasite Fig. 2. The zo nes are 图 1 微晶质白铁矿的选区电子衍射花样图 , 2 内华达卡林金矿中含 As 和 Au 白铁矿的 图 010 、030 反射斑来自多重衍射 。HR T EM 像 。显示与邻区相比相对富 As 的似带 Fig. 1 SA ED pat tern of t he microcrystalline 状区 ,后者可能是富 Au 的 。 Fig. 2 HR T EM image of an As2 and Au2bearing marcasite. The reflectio n spot s of 010 , 030 are marcasite f ro m Carlin mine of Nevada , showing f ro m multiple diff ractio n. band2li ke zo nes t hat are relatively rich in As wit h respect to t he neighboring area . It is p roposed t hat Au may be rich in t hese zo nes. ( ) relatively rich in As wit h respect to t he neighbo ring areas Fig. 3. The EDS spect ra do not show ( ) Au peaks because t he co ncent ratio n of Au is lower t han t he detectio n limit , 0 . 1 %. Aut ho r p ropo ses t hat t hese zo nes are also relatively rich in Au , o r , po sitio ns of real invisible Au in lat tice 3 + + st ruct ure. It is also p ropo sed t hat catio nic Auand Au were inco rpo rated into t he marcasite st ruct ure t hro ugh surf ace so rp tio n p rocess during t he marcasite crystallizatio n . Furt her crystallizatio n of t he marcasite crystal result s in t he local disto rtio n of t he polyhedral f ramewo r k as show n in t he HR T EM image in t he fo r m of t he band2like feat ure . Similar p heno meno n may also occur in Au2bearing microcrystalline p yrite . 图 3 带状区及其邻区的 X 射线能量散射谱图 。注意两个谱图中的 As 含量峰 ,Cu 的峰来自支承样品的铜网 () ( ) Fig. 3 EDS spect ra f ro m t he band2li ke zo ne lef tand it s neighboring areas right. Notice As co ntent peaks in bot h spect ra . Cu peaks are f ro m Cu grid holding t he specimen ( ) The associated illite and kaolinite are almo st Fe2f ree below EDS detectio n limit , w hich may i ndicate existence of S2rich fluid during Au mineralizatio n . Microcrystalline quartz associated ( ) wit h t he Au2bearing marcasite is rich in planar defect s t win bo undaries, w hich indicates f ast 13 crystallizatio n of quartz . 4 Inco rpo ratio n of Au and o t her t rivalent met als i nto mi nerals () The t race element s e . g. , rare eart h element s : R EEin minerals are widely used as a guide 14 , 15 to understanding genesis of minerals and rocks . It is impo rtant to understand t he inco rpo ra2 tio n of t he t race element s in minerals quantitatively. In t his paper , a new equatio n is developed minerals during equilibrium and no n2 fo r co rrelating and p redicting t he t race element s in equilibrium crystallizatio n . ( ) ( )bet ween a mineral e . g. , calcite and The partitio ning of a t race element e . g. , R EE aqueo us solutio n is generally exp ressed by t he dist ributio n coefficient , K: d ( )()( ) 1 X / X / m / m . K= TrCO CaCO TrCad 3 3 ( ) X , X w here , , m , and m are mole f ractio n of t race element Trcarbo nate in t he Tr Ca TrCO CaCO3 3 solid , are mole f ractio n of calcite in t he solid , co ncent ratio n of t race element in solutio n , and co n2 2 + cent ratio n of Cain solutio n , respectively. Fro m t heo retical co nsideratio n , t he system is assumed to be in equilibrium , and t he Kis d equilibrium dist ributio n coefficient o r t her mo dynamic dist ributio n coefficient . The dist ributio n coefficient deter mined f ro m no n2equilibrium crystallizatio n systems o r f ro m experiment s is called experimental dist ributio n coefficient o r no n2equilibrium dist ributio n coefficient , and it is exp ressed 15 )( ( ( ) ) K’= as X / X / m / m . In general , K’is larger t han Kfo r largedTrCO CaCO TrCa d d 3 3 catio ns. Fo r t he partitio ning of t rivalent R EE in calcite , we may w rite a reactio n of : 3 + 2 + () ()( ) 2/ 3M + 2 CaCO= M CO+ Ca, 3 2/ 3 3 o r , 3 + 2 + () ( ) ()2/ 3M + CaCO- Ca= M CO. 3 3 2/ 3 3 to t he The experimental dist ributio n coefficient is p ropo sed to be p ropo rtio nal reactio n energy 0 (Δ) () () Gof reactio n 2o r 3by : rxt 0 Δ- 2 . 303 R T lo g K’ = G. d()4 rxt 0 00003 + Δ Δ Δ . ()ΔΔ ()- G+ G- 2/ 3GG= G5 rxt f , TrCO f , CaCO f , Ca f , M 3 3 0000 5 3 + ( ) Δ Δ Δ Δ w here , G, G, G, and Gare standard 25C? , 10PaGibbs f reef , TrCO f , CaCO f , Ca M 3 3 2 + 3 + ( ) energies of fo r matio n of M CO, CaCO, Ca, and M , respectively. 2/ 3 3 3 ( ) () Because t race amo unt of co mpo nent s M COo r , TrCOin calcite will not change 2/ 3 3 3 (crystal st ruct ure of t he calcite , t herefo re , t he Gibbs f ree energies of fo r matio n fo r all fictive co m2 ) ( ) po nent wit h calcite st ruct ureM COco mpo nent s can be co rrelated by t he linear f ree energy 2/ 3 3 16 ,18 equatio n of : 0 03 + 3 + β + ( )ΔΔ b + r . 6 G= a Gf n , M M β In t his equatio n , t he coefficient s a , b , and characterize t he particular crystal of M L , V 3 + 19 3 + β( ) and ris t he io nic Shanno n - Prewit tradius of t he M catio n . The value of is related M to coo rdinatio n enviro nment of polyhedra o r t he flexibilit y fo r t he metal catio ns wit hin t he 16 ,18 0Δ is t he standard Gibbs f ree energies of fo r matio n of t he polyhedra. The parameter Gf , M vL 03 + Δ is standard no n2solvatio n energy f ro m a radiusΟ end2member solids , and t he parameter Gn , M based co rrectio n to t he standard Gibbs f ree energy of fo r matio n of t he aqueo us t rivalent catio n 03 + 19 ,20 3 + Δ M .The parameter Gcan be calculated using t he equatio n : n , M 0003 + 3 + 3 + Δ ()Δ Δ G, 7 = G+ Gf , M n , M s , M 03 + Δ w here Gis t he standard Gibbs f ree energy of solvatio n of t rivalent aqueo us catio n t hat can s , M 19 be calculated f ro m co nventio nal Bo r n solvatio n coefficient s fo r t he aqueo us catio nsacco rding to t he equatio n : 03 + 3 + Δ()ω (ε) G8 = 1/- 1. s , M M 3 + εω() () In t he equatio n 8, is dielect ric co nstant of water 78 . 47 at 25 C?. The parameter are M Bo r n solvatio n coefficient s fo r t he t rivalent catio ns , and can be calculated using t he equatio n : abs abs+ 3 + 3 + ()ωωωM - 9 3H. = M abs + + ω( ) In t he above equatio n ,is absolute Bo r n solvatio n coefficient of H 53 . 87 kcal/ mole, and H abs 3 +ωM is absolute Bo r n solvatio n coefficient s of t he t rivalent catio ns t hat are related to effective elec2 3 + ( )by t he relatio nship : t ro static radii of t he aqueo us io ns r Me , abs2 3 +3 + ω(×3 / 166 . 027 ()M = ) 10 r, e , M and 3 + 3 + ( ) ()r+ 3 ×0 . 094 nm. 11 r=M e , M The standard solvatio n energy and no n2solvatio n energy can be calculated based o n above () ( )equatio ns , and are listed in Table 1 . The Equatio n 6can be used fo r t he system of M CO 2/ 3 3 ) ( ( Table 1 , Fig. 1. By fit ting t he equatio n to t he existing t her mo dynamic data stabilit y co nstant s 表 1 离子半径 ,三价水合阳离子的热力学数据 ,预测的 lo g K’值 , log K的上限值 , dd 具有 REE( CO) 结构的 M( CO) 碳酸盐之 log K 值2 3 3 2/ 3 3 Ta ble 1 Ion ic ra dii , thermodyna mic data f or trivalent aqueous cations , and predicted log K’, dup2l imit of log K, and log KofM ( CO) carbonates with REE( CO) structure d 2/ 3 3 2 3 3 3 + ΔΔΔGGG rKlog sfnK’ K’ log log K K log log M ddd3 + M 3 + 3 + 3 + ( )( )( )( )( )( )Exper . Calc . nm M M M Exper . Calc . Calc . ()()()aq aq aq Al 0 . 053 - 288 . 10 - 115 . 38 172 . 73 - 3 . 50 - 5 . 73 6 . 49 Cr 0 . 062 - 276 . 92 - 51 . 50 225 . 42 - 1 . 28 - 3 . 88 8 . 34 Fe 0 . 065 - 273 . 11 - 4 . 12 268 . 99 - 0 . 39 - 3 . 12 9 . 10 Co 0 . 063 - 275 . 01 32 . 03 307 . 04 - 0 . 41 - 3 . 07 9 . 15 Ga 0 . 062 - 276 . 28 - 38 . 00 238 . 28 - 1 . 09 - 3 . 71 8 . 51 Ti 0 . 076 - 259 . 08 - 83 . 60 175 . 48 0 . 93 - 2 . 32 9 . 90 0 . 064 - 273 . 74 - 57 . 90 215 . 84 - 0 . 86 - 3 . 57 8 . 65 V Mn 0 . 058 - 281 . 46 - 20 . 30 261 . 16 - 1 . 76 - 4 . 21 8 . 02 Sc 0 . 081 - 253 . 25 - 140 . 20 113 . 05 1 . 21 - 2 . 26 9 . 96 0 . 095 - 237 . 77 51 . 30 289 . 07 4 . 05 - 0 . 01 12 . 21 Tl 0 . 096 - 236 . 71 19 . 79 256 . 50 3 . 92 - 0 . 20 12 . 03 Bi 0 . 081 - 253 . 25 - 23 . 40 229 . 85 2 . 03 - 1 . 43 10 . 79 In 0 . 092 - 240 . 99 - 163 . 80 77 . 19 2 . 28 - 1 . 68 10 . 54 Y 0 . 114 - 218 . 51 - 164 . 00 54 . 51 3 . 75 - 1 . 18 11 . 05 L a 3 . 62 11 . 13 0 . 107 - 225 . 39 - 161 . 60 63 . 79 3 . 43 - 1 . 19 11 . 03 Ce 3 . 53 11 . 03 0 . 106 - 226 . 39 - 162 . 60 63 . 79 3 . 37 - 1 . 21 11 . 01 Pr 3 . 49 0 . 104 - 228 . 41 - 160 . 60 67 . 81 3 . 26 - 1 . 23 10 . 99 Nd 3 . 18 11 . 00 0 . 106 - 226 . 39 - 158 . 00 68 . 39 3 . 40 - 1 . 18 11 . 05 Pm 0 . 100 - 232 . 52 - 159 . 10 73 . 42 2 . 99 - 1 . 32 10 . 90 Sm 10 . 83 3 . 06 0 . 098 - 234 . 60 - 137 . 30 97 . 30 2 . 99 - 1 . 23 10 . 99 Eu 2 . 89 0 . 097 - 235 . 65 - 158 . 60 77 . 05 2 . 76 - 1 . 42 10 . 80 Gd 2 . 75 10 . 73 0 . 093 - 239 . 91 - 159 . 50 80 . 41 2 . 40 - 1 . 60 10 . 62 Tb 2 . 51 0 . 092 - 240 . 99 - 158 . 70 82 . 29 2 . 31 - 1 . 65 10 . 58 Dy 2 . 41 10 . 50 0 . 091 - 242 . 08 - 161 . 40 80 . 68 2 . 20 - 1 . 72 10 . 50 Ho 1 . 99 0 . 089 - 244 . 26 - 159 . 90 84 . 36 2 . 00 - 1 . 82 10 . 40 Er 1 . 85 0 . 087 - 246 . 59 - 159 . 90 86 . 69 1 . 78 - 1 . 96 10 . 27 Tm 0 . 086 - 247 . 81 - 153 . 00 94 . 81 1 . 70 - 1 . 98 10 . 24 Yb 1 . 85 10 . 37 0 . 085 - 248 . 94 - 159 . 40 89 . 54 1 . 54 - 2 . 10 10 . 12 L u 0 . 112 - 220 . 45 - 113 . 88 106 . 57 4 . 02 - 0 . 82 11 . 41 U 0 . 108 - 224 . 39 - 138 . 15 86 . 24 3 . 65 - 1 . 01 11 . 21 Pu 0 . 110 - 222 . 41 - 123 . 59 98 . 82 3 . 86 - 0 . 89 11 . 33 Np 0 . 107 - 225 . 39 - 143 . 19 82 . 20 3 . 56 - 1 . 06 11 . 17 Am Au 0 . 085 - 248 . 71 103 . 60 352 . 31 3 . 40 - 0 . 22 12 . 00 19 , 20 14 Δ( ) Note : Radii and Gare f ro m references ; log K’values are f ro m reference ; log K of M COcarbo n2 f d2/ 3 321 , 22 ( ) ates wit h R EECOst ruct ure are f ro m references . 2 33 21 , 22 ) f ro m references , t he coefficient s in t he equatio n fo r t he M COst ruct ure f amily are 2/ 3 3 β ( ) ( ) calculated to be : a = 0 . 6570 , = 640 kcal/ mole n?m , and b = - 233 . 17 kcal/ mole. The discrepancies bet ween t he calculated and experimental values are wit hin 0 . 1 log unit . () () () () U sing equatio ns 4, 5, and 6, equatio n 12can be o btained : 0 0003 + 3 + 3 + βΔΔ()()Δ+ , Δ 12 - 2 . 303 R T log K’ = a b + rM - G+ G- 2/ 3GGn , M f ,CaCO f ,Ca f , M d3 o r , 003 3 + 3 + 3 + ()Δβ() Δ + - , 13a b + r2/ 3G- 2 . 303 R T log K’ = a Gn , M M f , M d w here , 3 00()Δ Δ 13b , b = b - G+ Gf , CaCO f , Ca 3 00( ) ( )Δ Δ are co nstant s fo r a given mineral calcite . Equatio n 13a Gand Gmay be f , CaCOf , Ca 3 rearranged as a linear relatio n of 3 003 + 3 + 3 + ()βΔΔ () = + b . 14 a G- 2 . 303 R T lo g K’- r+ 2/ 3Gf , M n , M dM ) ( By fit ting t he equatio n to t he existing no n2equilibrium dist ributio n coefficient s K’, t he d ( )β coefficient s in t he equatio n 14 fo r t he calcite are calculated to be : a = 0 . 6571 , = 580 3 ( ) ( ) kcal/ mole n?m , and = b - 216 . 39 kcal/ mole . The discrepancies bet ween calculated ( ) experimental values are wit hin 0 . 15 log unit Table 1. Figure 4 illust rates t he linear relatio nship () βof equatio n 14. The value of fo r K’relatio n is smaller t han t hat fo r bulk crystalline p hases , d w hich indicates t hat t he polyhedra enviro nment fo r co2p recipitatio n of R EE is mo re flexible t han t hat inside t he bulk calcite crystal . This also indicates t he flexible st ruct ural enviro nment at t he ( ) mineral - solutio n interf ace . Fast no n2equilibriumcrystallizatio n of calcite f reezes such kind of () st ruct ure into calcite o r , inco rpo rates high co ncent ratio n of R EE into t he calcite. The coefficient a fo r t he equilibrium relatio nship K d sho uld be same as t hat fo r no n2 equilibrium K’, because t he d slope a is a f unctio n of stoichio m2 16 , 17 β et ry .The coefficient fo r t he equilibrium Krelatio nship d sho uld be same as t hat fo r bulk ( crystals i . e . , 640 kcal/ mole ? ) nm . Therefo re , equilibrium Ksho uld be smaller t han no n2 d equilibrium K’, especially fo r d ( t he large catio ns e . g. , R EE , ) Au . Fro m t he t her mo dynamic () ( )图 4 方解石中 R EE 的非平衡分配系数 K’上及 M CO d2/ 3 3 point of view , t rivalent catio ns () 族中稀土碳酸盐相的稳定性常数 下之线性关系图will not fit into t he po sitio ns of Fig. 4 The diagram showing linear relatio nship for t he no n2equiΟ ) ( ( )Ca in calcite . In here , we just as2 librium dist ributio n coefficient K’of R EE in calcite upper d ( )and stability co nstant s of t he R EE2carbo nate p hases in M CO 2/ 3 3 sumes equilibrium Kfo r all d ()family lower t rivalent catio ns in calcite are () smaller t han o ne as an up2limit . The calculated up2limit values are also listed in t he Table 1 . () The data indicate t hat no n2equilibrium f ast crystallizatio n of calcite will inco rpo rate mo re R EE () and Au t han equilibrium crystallizatio n of calcite e . g. , large crystals. Recrystallizatio n of early2 fo r med fine grain crystals will remove R EE and Au f ro m t he crystals. The p rocesses may be also applied to t he inco rpo ratio n of Au and ot her element s into sulfides , such as p yrite and marcasite . Alt ho ugh t here are no such data fo r p yrite and marcasite , t he () general p rinciple is same . No n2equilibrium f ast crystallizatio n of p yrite and marcasite inco rpo2 ( ) rates mo re Au t han equilibrium slow crystallizatio n of p yrite and marcasite does , because t he ) ( no n2equilibrium dist ributio n coefficient K’is larger t han equilibrium dist ributio n coefficient d ( ) K. The sample f ro m Carlin gold o re depo sit co ntains large p yrite crystals and fine grain d ) ( micro meter levelmarcasite . Only t he fine grain crystals co ntain invisible Au t hat may be in t he 3 + + states of Auand/ o r Au . The fine grain marcasite also indicates no n2eqiluibrium crystalliza2 3 + tio n , because t her mo dynamic stable fo r m of FeSis p yrite . It is p ropo sed t hat catio nic Auwere 2 inco rpo rated into t he fine grain marcasite at t he marcasite - solutio n interf ace during f ast () crystallizatio n of marcasite . The interf ace st ruct ure e . g. , polyhedrais mo re flexible t han t hat inside t he bulk crystal . The partitio ning of Au in t he marcasite is co nt rolled by t he no n2 ) ( equilibrium dist ributio n coefficient K’. Furt her growt h of t he marcasite crystal inco rpo rates d t he Au and disto rted polyhedral enviro nment into t he crystal and result s in t he local disto rtio n of t he polyhedral f ramewo r k as show n in t he HR T EM image in t he fo r m of t he band2like feat ure . Similar p heno meno n may also occur in Au2bearing microcrystalline p yrite fo r med t hro ugh no n2 () equilibrium f ast crystallizatio n . Ackno wledgment : This wo r k is based upo n research co nducted at t he Transmissio n Elect ro n Micro scop y L abo rato ry in t he Depart ment of Eart h and Planetary Sciences of t he U niversit y of New Mexico , w hich is partially suppo rted by N SF , NA SA , and State of New Mexico . Aut ho r also t hanks N SF of China fo r partial suppo rt of t his st udy. This paper is dedicated to Professo r Gufeng L U O , fo r his co nt ributio n in mineralogy st udy and teaching fo r 45 years. 作者简介 : 徐惠芳 ,男 ,1964 年生 ,博士 ,现任美国新墨西哥大学地球与行星科学系研究员 、透射电镜 主任 ,主要从事环境矿物学和地球化学研究 。 Ref erences : 1 Cabri L J . The dist ributio n of t race p recious metals in minerals and mineral p roduct s J . Mineralo gical Magzine , 1992 , 56 : 2892308 . Bakken B M , Hochella J r . M F , Marshall A F and Turner A M . High2resolutio n microscop y of gold in un2 2 o xidized ore f ro m t he Carlin mine , Nevada J . Eco no mic Geolo gy , 1989 , 84 : 1712179 . 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