RDN: A SHALLOW MARINE VMS PROSPECT

Transcription

1 RDN: A SHALLOW MARINE VMS PROSPECT By Henry J. Awmack and Mark E. Baknes 1 KEYWORDS: Early t Middle Jurassic, Eskay Creek, Hazeltn Grup, lw-sulphidatin epithermal, shallw marine vlcangenic massive sulphide depsits. INTRODUCTION The RDN prperty, wned 100% by Rimfire Minerals Crpratin, is a shallw marine vlcangenic massive sulphide (VMS) prspect with striking similarities t Barrick Gld Crpratin s high-grade Eskay Creek depsit 40 kilmetres t the suth. The RDN prperty cvers 68 square kilmetres f muntainus terrain, apprximately 120 kilmetres nrthwest f Stewart, British Clumbia. Access t the prperty is by helicpter frm Bb 1 Equity Engineering Ltd., West Pender Street, Vancuver, B.C., V6C 1G8 Quinn airstrip, which lies n the Stewart-Cassiar highway 20 kilmetres t the east. The Eskay Creek access rad passes fifteen kilmetres sutheast f the RDN prperty. Eskay Creek, with prductin plus reserves f 3.9 millin unces Au and 175 millin unces Ag (Rgers, 2002), is cnsidered t be the prduct f a lw-sulphidatin epithermal system venting t the sea-flr in a shallw marine setting. As such, it cmbines sme f the features f Kurk-style VMS depsits with thse f lw-sulphidatin epithermal precius metal depsits. The RDN prperty shares a number f gelgical and gechemical characteristics with Eskay Creek, that frm the basis fr the RDN explratin mdel. EXPLORATION HISTORY Prir t 1987, n wrk had been recrded n the area cvered by the current RDN prperty. Extensive explratin, including 3,633 metres f diamnd drilling in W RDN Prperty N Highway 37 Frrest W N Kerr Fault RDN PROPERTY i ver R t I s k u 500km Mre Creek Eskay Rad Carcass Ck Eskay Creek LEGEND Alluvium Early t Middle Jurassic Hanging wall sequence Clastic sediments Basalt Ftwall sequence Felsic vlcanics Mnznite prphyry Wedge Zne 101.0g/t Au (cre) 1.95m Marcasite Gssan Jungle Anmaly 25.4g/t Au (flat) Dwnpur Creek 0 5 km W Palezic t Early Jurassic Intrusives, vlcanics and sediments Majr fault Bundary Zne 359.7g/t Au (cre) 0.45m W km Figure 1. RDN reginal and prperty gelgy (reginal gelgy adapted frm Lgan et al., 2000 and Alldrick et al., 1989). Explratin and Mining in British Clumbia

2 hles, was carried ut n it frm 1988 t 1992 by Nranda and thers, directed almst entirely at Au-bearing quartz-sulphide veins. At that time, quartz-sulphide veins were being develped int the Snip and Skyline mines, 40 kilmetres t the suthwest, and there was cnsiderable explratin fr vein mineralizatin thrughut the Iskut River district. The Eskay Creek depsit, 40 kilmetres suth f the RDN prperty, was discvered in 1988, but its VMS nature was nt widely recgnized until Despite recgnitin that the strata that hst Eskay Creek cntinue nrth and underlie the RDN prperty, the ptential fr Eskay Creek-style mineralizatin was barely investigated during this flurry f explratin. Pathfinder Resurces Ltd. carried ut three small explratin prgrams n the RDN prperty frm 1994 t 1996 and cnfirmed the basic features f the Eskay Creek analgy. Rimfire Minerals Crpratin cntinued t fcus n this mdel with extensive fieldwrk frm 1997 thrugh 1999, culminating in a 9 hle, 574 metre drill prgram. Newmnt Explratin f Canada Limited ptined the RDN prperty in early 2000 and carried ut a grund UTEM survey ver 6.7 kilmetres f Eskay-equivalent stratigraphy. In 2001, Newmnt drilled 13 hles ttalling 2,222 metres t test UTEM cnductrs in the vicinity f the Eskay-equivalent stratigraphic cntact. Ftwall Vlcanic Unit at Eskay Creek and the K-spar megacrystic feldspar prphyry t the Eskay Prphyry (Eskay Creek nmenclature frm Rth et al., 1999); cnsequently, this package is referred t here as the ftwall felsic sequence. Thleiitic basalt flws and lesser vlcaniclastic rcks verlie the felsic vlcanic rcks suth f Mre Creek. Pillws are prminent, particularly in the vicinity f the Marcasite Gssan and suth t the suthern prperty bundary, indicating submarine depsitin. The basalt is essentially unaltered, and chemically and texturally similar t the hanging wall basalts at Eskay Creek. Clastic sediments, mainly argillites and siltstnes, are interbedded with the basalts and becme dminant up sectin. Tgether, the basalt and clastic sediments are referred t here as the hanging wall sequence. The argillites near the base f the hanging wall sequence are cmmnly carbnaceus and lcally graphitic; pyrite is preserved as laminae and within pyritic clasts. Based primarily n lithgechemical and textural similarities in the basalt at Eskay Creek and RDN, the cntact between the felsic and basalt/sediment sequences is cnsidered crrelative t that which hsts Eskay Creek s 21 Zne stratifrm rebdies, and is referred t here as the Eskay-equivalent cntact. GEOLOGY The RDN prperty extends fr mre than 20 kilmetres alng the east side f the Frrest Kerr Fault, a nrtherly-trending, steeply-dipping nrmal fault f reginal extent. Palezic metasediments, metavlcanic rcks and plutns lie west f the Frrest Kerr Fault. East f the fault Meszic rcks f the Upper Triassic Stuhini Grup and Lwer t Middle Jurassic Hazeltn Grup predminate. The Stuhini Grup and the base f the Hazeltn Grup cnsist mainly f andesitic t basaltic vlcanic rcks and clastic sediments. The upper part f the Hazeltn Grup crrelates with Eskay Creek depsit strata. It cnsists f felsic vlcanic rcks, basalt and clastic sediments. On the RDN prperty, the Hazeltn Grup felsic vlcanic rcks can be split int tw packages. The first package cnsists f rhylitic flws and tuffs which are widespread nrth and west f Mre Creek; these are generally unmineralized and will nt be discussed further. The ther felsic rcks are assciated with a separate felsic centre suth f Mre Creek that extends fr 13 kilmetres suth t the suthern prperty bundary. This package cnsists dminantly f dacite and trachyte tuffs and flws, with very minr amunts f rhydacite and rhylite. Feldspar prphyries, lcally K-spar megacrystic, frm bth extrusive and intrusive phases in this felsic package. The felsic rcks are generally carbnate-altered; lcally they are flded by sericite, silica and/r ptassium feldspar alteratin. The main feldspar prphyry intrusive bdy is pervasively altered t sericite, clay, pyrite and lcal alunite. It frms a very prminent gssan with a large assciated ferricrete depsit. Lithgechemistry shws this secnd package f felsic vlcanic rcks t be similar t the Pht 1. Lking suthwest at altered and pyritized feldspar prphyry, frming prminent gssan, intruding cmagmatic dacitic vlcanic rcks in Dwnpur Creek. 66 Mines Branch

3 The RDN prperty is structurally cmplex. The Hazeltn Grup is dminated by nrtherly trending, lcally verturned, anticline-syncline pairs with steep axial surfaces. The main fault trends are nrtherly (parallel t the Frrest Kerr Fault), nrthwesterly and nrtheasterly. These are high angle faults, chpping the RDN prperty int a msaic f fault blcks. ESKAY CREEK-STYLE VMS PROSPECTS Mst pre-1994 wrk n the RDN prperty fcused n Au-rich quartz-sulphide veins in the altered ftwall felsic vlcanic rcks. This veining and alteratin are thught t be integral parts f a VMS hydrthermal system, bth at Eskay Creek and RDN. The submarine hydrthermal systems prduced base and precius metal-rich fluids which altered the ftwall felsics and depsited sulphide-bearing quartz veins, stckwrks and silicified znes in structural traps. Where these fluids vented t the sea flr, they became available fr depsitin as stratifrm sulphide layers. The Eskay-equivalent cntact between variably altered and mineralized ftwall felsic vlcanic rcks and unaltered hanging wall clastics and mafic vlcanic rcks can be traced fr 9 kilmetres nrth frm the suthern bundary f the RDN prperty. Because f its recessive nature, this cntact is rarely expsed n surface and has nly been penetrated in 7 drill sectins: ne at the Bundary Zne, ne at the Marcasite Gssan, and five in the Wedge Zne. The fllwing table summarizes significant drill intersectins frm the 52 drill hles. With the exceptin f hle RDN99-01, all intersectins are within the ftwall felsics. WEDGE ZONE TABLE 1 SIGNIFICANT RDN DRILL INTERSECTIONS Wedge Zne veining is within an 800 x 2,600 metre Au-Ag-As-Pb-Sb-Zn sil gechemical anmaly that verlies altered dacitic vlcanic rcks n the eastern side f the Carcass valley. Nranda discvered a number f discntinuus quartz-sulphide breccia veins in the Wedge Zne and directed mst f their drilling at them. These veins are generally hsted by barren sericite alteratin, pinch and swell dramatically, and are ffset by extensive small-scale crss-faults. Lcally they carry very high grades, such as intersectins f 1.95 metres f 101 g/tnne Au and 0.85 metres f 138 g/tnne Au in hle RG Generally, these veins are lcated 50 t 200 metres stratigraphically belw the tp f the felsic vlcanic rcks. A few f Nranda s westernmst hles were cllared in, r bttmed in, hanging wall argillite. This suggested that the Eskay-equivalent cntact runs nrtherly dwn the Carcass valley. Newmnt drilled 10 f their 13 hles in this Wedge Zne cntact area, hwever, by targeting UTEM cnductrs rather than stratigraphy, half f these hles were drilled entirely in either ftwall dacite r hanging wall clastics. Frm the 2001 Newmnt drilling it is clear that the Wedge Zne stratigraphy is verturned; it dips steeply t the east but tps are t the west, and is lcated n the west limb f a nrth-suth trending anticline cred by ftwall dacites. The stratigraphy crrespnds t a shallw marine setting, with bivalves and belemnites in the hanging wall clastics and lcal marn vlcaniclastic units. There are tw distinct vlcanic cycles at the stratigraphic tp f the ftwall dacite sequence. The best VMS ptential is cnsidered t be at the tp f each cycle in carbnaceus and tuffaceus strata. Cycle 1 cnsists f a sulphide-bearing and veined subvlcanic prphyry within an emergent dme and may represent a vlcanic/hydrthermal surce t the Drill Zne Frm T Length Au Ag Cu Pb Zn Hle (m) (m) (m) (g/t) (g/t) (%) (%) (%) RG90-6 Wedge RG90-7 Wedge RG90-11 Wedge RG90-15 Wedge RG91-16 Bundary N/A 0.22 N/A N/A RG91-20 Wedge RG91-21 Wedge RG91-22 Wedge RDN99-01 Jungle RDN01-17 Wedge RDN01-20 Wedge Explratin and Mining in British Clumbia

4 CARCASS GLACIER Fr Kerr Fault rest 10,200N Carcass Ck RDN W N RDN01-13 RDN01-22 RG91-24 Carcass Fault Early t Middle Jurassic Hanging wall sequence Clastic sediments Basalt and dirite Ftwall sequence Felsic vlcanics Early Jurassic Mnznite prphyry Palezic Intrusives, vlcanics and sediments 9400N 9600N RDN01-10,11 RDN N 8850N RDN01-18 RG90-14 RG90-20 RG91-28 RDN01-19 RG91-22 RG90-5 RDN01-20 RDN01-17 RG90-4 RDN99-08 RG90-3 RG90-15 RG90-2 RG90-6,7 RG91-21 RG90-1 RG91-23 RG90-10 GLACIER Wedge sil anmaly Wedge Au-Ag-As-Pb-Sb-Zn sil anmaly Tp f cycle 2 Jungle Au-As sil anmaly RG m RG90-9 RG90-11 RG W Gssan Ck Jungle sil anmaly RDN99-01 RDN99-07 RG90-12,13 Figure 2. Wedge Zne gelgy, sil gechemical anmaly, and drill hles. mineralizing system (nly ne hle intersected the tp f Cycle 1). Widespread alteratin and mineralizatin were develped synchrnusly with depsitin f Cycle 2 and d nt extend abve the tp f Cycle 2. The carbnaceus unit at the tp f Cycle 2 is a preferential lcus fr faults, but the vlcanic-sedimentary depsitinal cntact appears t be preserved in sme f the hles. Alteratin and mineralizatin in the upper part f the ftwall dacites is quite different frm that related t deeper ftwall veining drilled by Nranda. In the shallwer setting, sulphide mineralizatin (including sphalerite, galena, tetrahedrite and rpiment) is mre pervasive and diffuse thrughut brad alteratin znes, rather than in discrete, well-defined quartz-sulphide veins. A siliceus breccia, with a massive chalcpyrite clast, at the tp f Cycle 2 (RDN01-17, m, 3.8 g/tnne Au) culd represent a vlcaniclastic breccia partially derived frm stratifrm sulphides. The Wedge Zne represents a ftwall alteratin zne that is mre than 2.5 kilmetres lng in a shallw marine setting. Newmnt s 2001 drill campaigns targeted the tp f Cycle 2 and intersected it n 3 sectins in the Carcass valley. Nranda als intersected this cntact further suth, s it has been cut n a ttal f 5 sectins (8850N, 8900N, 9400N, 9600N and 10200N). This leaves gaps frm suth t nrth f 50, 500, 200 and 600 metres f untested ptential. Only sectin 9400N has been drilled sufficiently t btain a reasnable picture f the stratigraphy and structure. Evidence f increasing metal values (including Cu) and increases in unit thickness tward pssible grwth faults favur drilling int the 500 metre gap suth f sectin 9400N. Mre than 2 km f the Eskay-equivalent cntact at the tp f Cycle 2 remains undrilled suth frm sectin 8850N t Cal Creek, and mst f this area is within the Wedge Zne sil anmaly. JUNGLE ANOMALY The Jungle Anmaly is a prnunced 100 x 450 metre Au+As±Ag±Pb sil gechemical anmaly in an area with little utcrp. Within the anmaly area, a cbble f pyritic, silicified argillite that is cut by quartz veinlets assayed Mines Branch

5 W 7600E 7700E 7800E 7875E E 1200m 1150m FORREST KERR FAULT PROJECTION RDN ,270 verburden RDN , 270 RDN , 090 verburden RDN , 280 RDN , g/t Au, 3110ppm Cu, 918ppm Pb, 5.67% Zn/0.5m RG91-22 (NORANDA) -45, 100 TD 152.7m Altered felsic cntact breccia TD m ~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3.75g/t Au, 5220ppm Cu, 730ppm Pb, 1755ppm Zn/1.5m 3.88g/t Au, 1460ppm Cu,1.62% Pb, 5.56% Zn/1.0m 1100m 7.06g/t Au, 2960ppm Cu, 305ppm Pb, 4.62% Zn/0.3m 1050m Fine-Grained Sediments (Hanging Wall) TD 152.7m 0.89g/t Au, 302ppm Cu, 144ppm Pb, 120ppm Zn/1.0m TD m Altered Felsic Vlcanics (Ftwall) silica, sericite, k-feldspar alteratin with disseminated pyrite,galena, sphalerite, tetrahedrite, tennantite, rpiment METRES 0 50 TD m Figure 3. Wedge Zne sectin 9400N, lking nrth. g/tnne Au with elevated As, Hg, Pb and Zn. A cluster f pyritic, slightly carbnaceus chert bulders, that culd represent a silica-pyrite exhalite, were fund nearby. The Jungle Anmaly is underlain by the hanging wall clastic/mafic vlcanic sequence. It is stratigraphically dwn-sectin frm the nly expsures in the area and the cntact with underlying felsic vlcanic rcks might be relatively shallw. Tw hles were drilled int the Jungle Anmaly in 1999 t test the hypthesis that it represented leakage frm an Eskay Creek-style VMS system int the verlying clastic/mafic hanging wall sequence. Due t grund cnditins, bth hles had t be abandned befre reaching their target depth. The hles intersected weakly elevated levels f Au and As, including 5.19 g/tnne Au acrss 1.1 metre, but cncentratins were nt high enugh t explain the sil anmaly. Except fr the Wedge zne area, the hanging wall sequence in this area cntrasts sharply with that elsewhere n the prperty. Elsewhere the hanging wall sequence is devid f bth veining and anmalus metals. Althugh the Jungle Anmaly culd simply reflect epigenetic mineralizatin, its ptential fr stratifrm sulphides remains untested. MARCASITE GOSSAN The Marcasite Gssan, lcated just t the east f Dwnpur Creek, cnsists f tw stacked ftwall dacite flw-dmes that have been altered and are cut by stckwrk mineralizatin. Peperitic cntacts indicate emplacement at r near the sea flr. Late magmatic t hydrthermal alteratin f the dacite, vein stckwrks and preservatin f clastic pyrite-marcasite are evidence f venting f hydrthermal fluids t the sea flr. Epithermal affinities are shwn by: the presence f chalcedny, pyrbitumen and marcasite; by cllfrm vein textures; by elevated As, Sb and Hg levels; and by the irregular, anastmsing, mrphlgy f the vein stckwrks. Hles RDN99-05 and -06 cut a cmplete sectin acrss the Marcasite Gssan, frm the hanging wall pillw Explratin and Mining in British Clumbia

6 Pht 2. Clastic massive pyrite-marcasite flat frm Marcasite Gssan (bttm). Fr textural cmparisn, clastic massive sulphide-sulphsalt re frm 21B Zne at Eskay Creek (tp). basalts t the ftwall Lwer Marcasite Gssan flw-dme. The drill cre shws that cntacts are depsitinal rather than tectnic, and stratigraphy is upright with mderate east dips. The prperty gelgy indicates that the hles cut the east limb f an anticline whse western limb was truncated by faulting alng Dwnpur Creek. A 70-metre thick basin f variably graphitic and pyritic mudstne, siltstne and wacke lies between the ftwall Upper Marcasite Gssan flw-dme and the base f the hanging wall pillw basalts. Eskay Creek s Cntact Mudstne, which hsts the 21 Zne rebdies, is in a similar stratigraphic psitin. An altered felsite sill within the clastics abve the Upper Marcasite Gssan is chemically identical t the lw-titanium Eskay Rhylite and ccupies a similar stratigraphic psitin. Despite elevated As, Sb and Hg levels, precius metal values t date at the Marcasite Gssan are very lw. Hles RDN99-05 and -06 were drilled thrugh the apex f the ftwall dacite dmes and did nt encunter any stratifrm massive sulphides. Better ptential fr accumulatin f massive sulphides might be fund alng the flanks f the dme. BOUNDARY ZONE The Bundary Zne, lcated immediately nrth f the RDN prperty s suthern bundary, cnsists f a grup f narrw, discntinuus chalcpyrite-pyrite-quartz-calcite veins. These are hsted by marn felsic vlcanic rcks and have chlrite-hematite alteratin envelpes. Sme veins are planar, with lcal cckade textures but thers cntain blebby aggregatins f sulphides. Veins average just a few centimetres in width and their wallrcks are nt auriferus. Gld values can be extremely high; hle RG91-16 intersected 45 centimetres grading 360 g/tnne Au. The Eskay-equivalent felsic/basalt cntact is prjected t lie <100 metres stratigraphically abve the Bundary Zne veining, but is nt expsed and has nt been drilled. The pssibility that the Bundary Zne veining represents a ftwall stckwrk t Eskay Creek-style Au-rich stratifrm sulphides is suggested by its psitin near the tp f the felsic vlcanic sequence, chlritic alteratin, high sulphide abundance relative t quartz cntent f veins, and high Au and Cu cncentratins. Hle RDN01-16 was drilled 130 metres nrth f the RDN s suthern bundary, int a series f debris flws near tw faults that are interpreted t be synvlcanic. Althugh this may represent part f the Eskay-equivalent cntact, it sheds little infrmatin n its ptential in the Bundary Zne area because veining and alteratin are entirely sutheast f the synvlcanic faults. DISCUSSION AND CONCLUSIONS The Eskay Creek VMS depsit cntains 3.9 millin unces Au and 175 millin unces Ag. Given its exceptinally high Au and Ag grades and lw prductin cst, it frms a very attractive explratin target. The key t finding a similar depsit is t lcate shallw marine rcks in a similar envirnment within a precius metal-rich vlcanic arc. The RDN prperty, lcated 40 kilmetres nrth f Eskay Creek, is underlain by strata that crrelate with the Eskay sequence and fulfils these criteria. In additin, it demnstrates a number f reginal-scale indicatrs cnsidered imprtant fr the develpment f a stratifrm, shallw marine vlcangenic massive sulphide Au-Ag depsit like Eskay Creek. Underlying strata crrelate with the tp f the Early t Middle Jurassic Hazeltn Grup. The prperty lies n the Harrymel/Frrest Kerr reginal fault system, which may have lcalized felsic centres and rifting. Bimdal vl- 70 Mines Branch

7 canism ccurs with felsic and basaltic end members. The basalt analysed frm RDN is chemically and texturally similar t Eskay Creek s, indicating lcal rifting. As well, the felsic vlcanic rcks include a felsite sill that is chemically similar t the Eskay Rhylite. Evidence f shallw marine depsitin is strng: pillws in the basalts, peperites and shallw water fssils. Vlcanic centres are indicated by ptassic feldspar-megacrystic prphyry intrusins. These are pyritic and highly altered, indicating hydrthermal activity. Chemical analyses indicate that they are very similar t the Eskay Prphyry. Other favurable indicatrs include: widespread alteratin f the felsic vlcanic rcks and structurally-cntrlled Au-Ag-base metal veining within them; synvlcanic faulting that led t frmatin f restricted basins; lw-sulphidatin epithermal features, including elevated As-Sb-Hg cntents and presence f rpiment, sulphsalts, chalcedny and pyrbitumen. On the RDN prperty, the cntact between ftwall felsic vlcanic rcks aging wall sequence f fine marine clastics and mafic vlcanic rcks has been traced mre than 9 kilmetres. Drilling in 1999 and 2001 shwed that this cntact is depsitinal rather than tectnic and strengthened the stratigraphic and lithgechemical analgy with Eskay Creek. Fur targets n the prperty with ptential fr Eskay Creek-style stratifrm sulphides are: the Wedge Zne, Jungle Anmaly, Marcasite Gssan and Bundary Zne. Cmpelling evidence at the Marcasite Gssan indicates that the tw dacite dmes identified were emplaced at r near the sea flr. Subsequent late magmatic t early hydrthermal fluids passed thrugh the dmes, causing widespread Kspar-silica flding and stckwrk veining, and vented t the sea flr where they depsited clastic massive sulphides. Althugh the Marcasite Gssan is deficient in base and precius metals, it demnstrates that vlcangenic massive sulphides were being depsited n the RDN prperty at the same felsic/basalt cntact as stratifrm rebdies at Eskay Creek. Evidence frm the 2001 Wedge Zne drilling is less cnclusive but the Wedge Zne appears t represent anther shallw-marine hydrthermal system. At the Wedge Zne, hwever, Au and base metals are enriched, and a clast f massive chalcpyrite, pssibly derived frm stratifrm sulphides, is present in a gld-bearing breccia at the tp f the felsic sectin. The Jungle Anmaly and Bundary Zne have gechemical anmalies and high-grade veining in the vicinity f the Eskay-equivalent stratigraphic cntact and require further testing. REFERENCES Awmack, H.J. (1999): 1999 gelgical, gechemical, gephysical and diamnd drilling reprt n the RDN 1-18 claims; B.C. Ministry f Energy and Mines, Assessment Reprt 26, 184 pages. Alldrick, D.J., Brittn, J.M, Webster, I.C.L. and Russell, C.W.P. (1989): Gelgy and mineral depsits f the Unuk area (NTS 104B/7E, 104B/8W, 104B/9W, 104B/10E); B.C. Ministry f Energy, Mines and Petrleum Resurces, (1:50,000), Open File Lgan, J.M., Drbe, J.R. and McClelland, W.C. (2000): Gelgy f the Frrest Kerr - Mess Creek area, nrthwestern British Clumbia (NTS 104B/10, 15 and 104G/2 & 7W); B.C. Ministry f Energy and Mines, Bulletin 104, 164 pages. Rgers, J.A. (2002): The Eskay Creek gld and silver mine: reserve pprtunities and explratin success created frm metallurgical diversity in a cmplex mineralized system in nrthwestern British Clumbia; CIM, abstracts fr 2002 AGM. Rth, T., Thmpsn, J.F.H. and Barrett, T.J. (1999): The precius metal-rich Eskay Creek depsit, nrthwestern British Clumbia; in Vlcanic-assciated massive sulfide depsits: prcesses and examples in mdern and ancient settings, Barrie, C.T. and Hanningtn, M.D., Editrs, Reviews in Ecnmic Gelgy, vlume 8, pages Explratin and Mining in British Clumbia

8 72 Mines Branch