Rom. J. Mineral Deposits, 77, p. Bucure,şti, 1996

NATIVE GOLD-BEARING MINERAL ASSEMBLAGES IN THE MĂGURA-FĂERAG HYDROTHERMAL VEIN

DEPOSIT (METALIFERI MOUNTAINS)

Eugen ORLANDEA, Gheorghe VELCIOV

MINEXFOR S.A. Str. Minerului, nr. 2,2700 Deva.

words: Native gold. Hydrothermal veins. Porphyry copper. Au:Ag ratio. Alterations. Metaliferi Mountains.

Abstract: At least two mineralization stages contain native gold at Măgura-Fă.eragj the first one consists of pyrite, rutile, arsenopyrite, chal­copyrite and the other one is represented by pyrite, Pb-Cu sulphosalt5, quartz and barite. ore veins are located in Neogene andesites showing pervasive phyllic-argillic alterations. The propylitization marginal parts of alteration zones. Locally, thepotassic alteration (secondary biotite) i5 developed and a proximal position against the ore veins. It is indicative of gold presence (positive metallotect). Taking into &ccount subvolcanic character of the andesite bodies aud the ma-jor structural setting defined as island arc, it i5 presumed a porphyry copper system at depth. Skorodite is the area the first time.

The Măgura-Făerag eruptive structure is situated the part the Săcă:râmb post-tectonic basin, a unit which nrpSlPT'VPSI a subsequent Neogene volcanic com-

. plex, the result of an andesitic volcanism re­lated to an "island arc" major tectonic struc­ture. The Neogene volcanics are associated with intramontane molasse formations, locally overlying Mesozoic ophiolitic and/or ca.l­careous flysch basement.

MINEXFOR S.A. began the system-atic explorat ion deposit in 1980; in the period 1957-1959 and 1965-1967- enter-prises and ca.rried sporadic re-search in The experts' interest in this deposit concomitantly with

start ing of the explorat ion works. In this re­spect it is to note the by Cioflică et (1966), Uduba.§a et al. (1982, 1984), Bordea, Pop (1989). The porphyry

structures in the Metaliferi Mts, similar in some to the Măgura-Făerag zone, were described by Borco§ et al. (1980, 1984), BO!~tinescu (1981, 1984) and Vlad (1983).

The known gold-silver, subordinately lead­ZInC, located in the Mă­gura, Mă.cie§ul, Custura andesitic bodies and related is six systems generally trending NNW-SSE or Among them, important in economic is West Măgura vein group, as moat of the native gold occurrences identified here (Fig.1).

- ............... b

2 3 4 /' , +

t

+ +

'l-

t +

,','~1 ~I "

+ ~. +

-+ +

+

+ +

+

+ +

+

J \

+ + + \

+ + . .L I UlliTTTL7 \1

+ + +

+ +

+ +

Zone uauoaşa., 1983, unpublished data, 1, quartz andesues

2, rQcks marls, sandstones (Lower Miocene): 3, Mesozoic

NATNE GQLD-BEARTNG MINERAL ASSEMBLAGES 23

exploration this vein group has been achieved at five horizons, summing up on the vertical 180

The evaluation of the results outlines both a zonality of deposition of the metallîc elements from the source geothermal system and a hy­pogene alteration the hornblende andesite rocks of Barza type, which hosts almost exclu-sively vein mineralizations.

Native gold assemblages 8)ld

parageneses

In the lower (-140 absolute height 263 m) octur rutile-pyrite-chalcopyrite­native gold±sphalerite, the paragenesis pyrite­chalcopyrite-native gold being significant for gold. The of sphalerite chaJcopy­rite is subordinate from the quantitative point

Gold.Two generations of gold are present. The generation was identified lamellae1

contorted plates, dendritoid forms, flattened trigonal outlines on

crusts or in microvoids of white-milky or grey bipyramidal quartz of first generation. Gol~

crystals display always well-developed octahe-The mineralogical, geochemical dron faces, whereas the tetrahedron faces can

and field evidence poited out the presence of at be presumed only in few cases. It is to note the two mineralization stages: the gold-silver dendritoidal forms in marginal zones the

stage, especially characterizes the western part native gold foils constituted undoubtedly of (Francisca, Rudolf, Iosif, Ludovica crystalline individuals. quasipar­veins) and the lead-zinc stage, dominantly oc- ' allel trend of the extremely fiattened crystals curs in the eastern part of the Măgura struc- which form foils points a oneway hydrother­ture (Măgura vein) (Fig. 1, 2 A, 2 B). In mal flux and a rapid growth of the crystals in

opinion, the median zone (Florian, Va,na dynamic system controlled by tectonic Neagră veins) with a gold-silver, subordinately factor. zinc character, corresponds to the overlapping NatÎve the second generation oc­of the two mÎneralization cycles. It is also pos- curs either as dendrites, a moss covering

this assemblage might have a distict the translucent grey-viola.ceous quartz crystals position in the general evolution trend of the with long prismatic habit and short rhombo­postmagmatic solutions (Fig. A). hedron faces, or rounded inclusions ar­

Gold-silver stage In the upper horizon (Tina Neagră - abso-

height the meta11îc rnineral as-semblage is defined by the succesion: pyrite­arsenopyrite-native gold-chalcopyrite±sphale­rite in a quartz and clay minerals gangue. Sig­nificant parageneses for native gold are, as fol­lows: quartz-native gold, quartz-arsenopyrite­chalcopyrite-native gold, quartz-arsenopyrite­native gold (Fig. 2 C).

At depth the identified metallic eraI assemblage consists of: rutile±i1menite­pyrite-arsenopyrite-native gold, the parage­neses quartz-native gold and quartz-pyrite­arsenopyrite-native gold being of great impor­tance.

senopyrite or more rarely chalcopyrite. Generally, alI gold crystals described far

are typical of the gold deposits found at a shallow' or depth, similar identical forms occurring in the Musariu, Valea Morii (Berbeleac, 1985) ore deposits as as ore deposîts in NW Russia (e.g. Balei ore deposit

Petrovaskaia, 1973). Pyrite occurs as hipidiomorphic-idiomorph­singie crystals (pentagonal dodecahedron

forms prevailing) or as small crystal cIus­ters which, in the vein influence zones, are found an the contour or inside the rnelanocrate crystals, associated with rutile, arsenopy­rite, iron oxides and hydroxides (hematite ?). Pyrite,sphalerite, pyritea!senopyrite in­tergrowths with a concentrical zonary aspect

21 Gh. VELCIOV

UJ + .;- <'01

e ...

~ :l +

+

..,. ... + + + .;- + + ..- + ..- +

+ + + + + + + + + + -1- -1- + + + +

+ + + + ... -1- + + .;-

+ + .;- + .;- + + + + + + ... + + + + + ...

+ + + + + + ... + "'" + + + + ... + + + -1-

+ + ... + + + J; E E e

.+ -1- + b S + ~ + S + + ... • I I i + +

.;- + + + + ... :l + -1-u

+ + -1-., ... c: C N N +f ... I ... ... ...

.il t:I.

..$ ... .c\ ,\ M

"\ m

Fig. 2 A - Geological cross-section through the Măgura-Făerag ore deposit with the vertical distributioll of the major elements (Legend: see Fig. 1).

Fig. 2 B - Sketch with the distribution of the mineral assemblages. 1, quartz-native gold-arsenopyritej 2, pyrite-chalcopyrite-native gold; 3, common gold.

2 C - Sketch with the distribution of the alteration fades (horizontal section); 1, phyllic-argiHic zone; 2, propylitic zone.

NATNE GOLD-BEARING MINERAL ASSEMBLAGES 25

of "atolls" are Chalcopyrite

pyrite or occurs crystals, alone or associated with pyrîte which is corroded by it.

A rsenopyrite is almost always found in asso­eiation with native gold, as small crystals with an elongated rhombic, more rarely isometric habit, in places polycrystalline ag-gregates, locally smalI swarm-like clusters; frequently, native gold in-

structure (Măgura , Generally, the succession

is: pyrite, chalcopyrite, marca.site, arsenopyrite, tetrahedrite, galena, bournonite, jamesonite, plumosite, native gold, native sil­ver. The gangue is constituted of quartz (de­posited within a wide range of temperature), barite, c1ay minerals, gypsum, zeolites (natro-

clusions of idiomorphic or Sphalerite, is iron-rich cubic or

. and forms xenomorphic masses subsequent to habit, usually grouped as aggregates corroded pyrite. Generally, it does not show calcopy- by subsequently deposited minerals. rite exsolutions, being often breceiated and ce- Chalcopyrite generally corrodes pyrite and mented by quartz. Locally, sphalerite is asso- locally sphalerite, galena and tetrahedritej eiated with arsenopyrite, occurring as impreg- covelline, chalcocite and bornite form at its nations in rock it substitutes or corrodes . least two generations the amphibole case of this mineral

Silver mineral", silver, silver sul-phides and not been found in the parageneses by us in this mineralization phase. The high value of the Au/ Ag ratio resulting from the chemi cal anal­yses earried out on samples from gold-silver veins points out that silver might form solid solutions with gold in pyrite and arsenopyrite.

The assemblage parageneses described above, the shape rninerals and the re-lationships the gangue min-erals (quartz±clay 1 the geothermo-metric measurements and Pop, 1989) indicate a formation temperature of about 300oC, corresponding to the final hipother­mal and hipomesothermal phase. The gold­arsenopyrite and gold-quartz assemblage is, in this case, of a higher temperature. It is to note the (Bordea and Pop, 1989) mineral assemblages in the gold together with ru-tîle, suggests gold from high-temperature

Lead-zinc The ore specific to this

. . mIcroscopIC

occurs frequently with a rhombic

double and triple interpenetrating twins after (230) or as aggregates with a characteristic in­dented contour. As a mineralogical novelty for the Măgura structure it is to note the sec­ondary formation on arsenopyrite crystals of

and/or brown orA>'A"

iron hydroxides.

frequently variety ( cleiophane),

with galena posited), tetrahedrite and chalcopyrite (exso­lutions structures).

Marcasite shows at least two distinct gener­ations:

- nests or isolated crystals with a rhombic 10, 110, 014 are

cor~ode pyri te

~ reniform~colIomorph aggregates tuted of micro- or cryptocrystalline prismatic

radiary disposition.

deposited at

26 E. Gh. VELCIOV

3 - Distribu tion of the veins in the Tina horizon (A) with details on the position of tbe alterat ion zones aud of the metallic mineral assemblages (B,

B: 1, alteration (biotite, hydromica, sericite); 2, clay minerals (mite, kaolinite) and carbonates; 3, ailica and hematite banda; 4, white quartz (bipyra­mida! crystals); 5, grey or violet quartz (prismatic habit); 6, marcasite-sphalerite-

Î, native 1 (plates, blades and flattened cryst.als )-arsenopyrite; 8, gold II (denrlrites);

C: 1, phyllic-argillic±pyrite alteratiou; 2, silicified andesite, hydrothermal breccias with pyrite, arsenopyrite, sphalerite, galena±chalcopyrite; 3, fissures and min-eralized veins with pyrite, marcasite, aphalerite, galena , clay carbonates; D: shapes of the native

corresponding to the second of mineralization, occurs as spangles, crys­tallosols, or included within the sulphides and sulphosalts network. The assocÎa-

small geodes, be of ori­gin considering its strong sulphophile charac­ter.

Taking account results of native with iron oxihydroxides

goethite-hydrogoethite the sec­ondary by mobilizat ion and deposition from fluids with meteoric supply. It is possible that silver, which occurs usually in

mineralogical-petrographical studies (Bordea & Pop, 1989) this association is considered to characterize a wider temperature interval cor-

to meso-epithermal phase, deposited from colloidal or almost coHoidal

texture clay als association (felt, fibrous a.ggregates) sug­

In the lower horizons this facies is usua.lly in- gests their formation as a result of chlorite al­tensely overprinted by subsequent alterations teration. In some thin sections, cryptocrys-

28

talline aggregatea clay minerals, which pre-serve relict islanda fibroua chlorite, have

a of fad, chlorite, subordinately assocÎated with carbonates and iron oxide/hydroxides, was formed at the ex­pense of amphibole. this case, minor albite can be found at the expense of feldspars in the matrix sericite.

neomineral assemblage described cor­responds to a chloritizaiion-propylitization most overprinted by effects of sub-sequent alterations.

Considering the whole enrooted structure, the phyllic-argiUic zone is widely developed in the western intrusion where Au-Ag

occur, symmetrically bordered by propylitization-chloritization zone with chlo­rite, albite, minerals, iron oxide/hydroxides especÎally developed in Măgura area, as weB as the westernmost part structure. In alteration stage the fluids from the geothermal system had a reduced metaHogene supply, at least in case

>o;o"o.U,'," elements: gold, silver, Pyrite is present as

nations and nests in aU the identified neomin­galena and ar­

senopyrite usually display an texture in rocks in the vicinity of the vein fractures. However, it is to note the constant

of chalcopyrite in the argiHic assocÎations at the level of the lower horizon (-140 m).

Significance of the Au-Ag Behaviour of the minor and trace

elements

of the gold-silver ratio is nificant in case of the Măgura as it represents an argument in favour of the depo­sit ion of mineralization during two main stages. Thus, in case of the veins from

West Măgura group, the Au:Ag ratio shows val ues bet ween 1/10 and 1/100, whereas western veins it

VELCIOV

displays a value 1/2 1/20. The small<;:r values of the ratio, recorded especially in the Măgura vein, correspond in our opin­ion to a lower-temperature mineralization de­posited during a from kaline solutions. The high values of tio the Au-Ag out the mineralization deposition during a primary higher temperature from high alkaline

Some of the high values of the gold­silver in Măgura vein are due to a pri­mary circulation, with the deposition of a high

quartz-gold-arsenopyrite parage­nesis. It is obvious the correlation of the gold content and the value of gold­silver This situation suggests that a large amount of native gold is associated to the mineralization stage.

regards the minor and trace elements in vein and in

the influence zones of the fractures, the num-ber effectuated so does not make possible a on be-haviour. However, it is to mention for arsenÎc (1500-3000 ppm), which are gen­erally correlated with of antimonium and the absence native gold veins. In this case the Au-Ag as­semblage indicates a higher temperature of hydrothermal fluids, as it is well known larger temperature interval within which ar­senic can occur'in the High

(more than 50 ppm) are also observed for V, Ti, B, Mn, Ba.

Structural and genetic conditions of the mÎneralizatÎon

In order to understand the Tertiary met­the Măgura ore deposit, sev­

eraI specifications are necessary regarding the general structural framework, the sha.pe and depth of of the Măgura andesitic body.

already mentioned the host rock mineralizations is repre5ented by the am-

NATNE GOLD-BEARING MINERAL ASSEMBLAGES 29

phibole (±quartz) andesite of Barza type with phenocrysts/matrix ratio ranging from 5/3 to The of (An36 <19), amphibole hornblende) and sparsely quartz as well as the microcrystalline groundmass of randomly orientated plagio­clase (±quartz) are characteristic of these rocks. Generally the present mClp­ient alltometamorphic alteration of type which consists especially in the chloritiza­tion of amphibole and the albitization of pla­gioclase.

Both mg

the surface at aU the intrusions within the delimited the

mm­struc-

In

zone, of a pile of clayey-sandy­marly sedimentary rocks, intensely tectonized and transposed to the vertical. These Bade­nian (ante-Badenian deposits obvious hydrothermal alterations tion, argillization, sericitization), impregna­tions with ~re minerals, recrystallizations. In­jections of andesitic material into sedimentary rocks contact are present,

The hypogene shows obvious and pervasive character in the western Întru­sion which encompasses the Au-Ag veins. It is worth mentioning the northern enrootment of this revealed descendent vertical drillings the horizon.

AlI structural data made uş consider the subvolcanic character for the amphibole­bearing andesite-body in the West Măgura ore The subvolcanic intru-ded of the s.1. (Jurassic~Middle vol-canics), Miocene sedimentary deposits and previous Neogene volcanic sequence. It is to note the almost exclusive presence ero-sIon the rocks by the body, situation ab-sence of the breccia pipe typical of structures of this type can be explained.

There are several observations of impor­tance in the deciphering of the metallogenetic evolution associated to the Măgura subvol-

canic structure, e.g.: - zonality of the hypogene alterat.ion fuies,

by a phillic~arginic zone encompassing the mineralizations bor-dered by a propylitized-chloritized zone with a variable degree of intensitYi

- constant presence of chalcopyrite as disseminations-impregnations at level of the horizon, as of the gold-pyrite-chalcopyrite paragenesis. copper minerals (chalcopyrite, tetrahedrite more fre­quently occur also in the vein fractures inter-

this level, particularly Măgura

vein; - pinching out Au-Ag (Vâna

Neagră, Florian) in the depth against the background of a more intense fissuration and argillic alterations;

presence the oxides (rutile~î1menite) determined associa-tions, which point to the origin of the gener­ating solutions in partially oxidated magmas;

- control of the mineralization and emplace-ment the subvolcamc body B) by the and regional tectonic

AH this stresses out the exÎstence of a porphyry-copper system which would corre­spond to a primary mineralization stage over-

the of the su bvolcano (dome zone), by mineralizations and subordinately by base-metal mineralizations corresponding to the two mineralization stages separated by us. Within this context, we es-

that beneath lower level western there are theorethical

of development of copper concentra­tions in porphyry system, probably associated to the potassic zone.

The development of the mineralization pro-cesses discontinuous, at least as the

stage and metal one. two pulsatory stages strictly delimited temporally are stressed out by the effects of the marked syntectonism in the deposition of the miner­alizations closely connected with the spatial delimitation of the two mineralization types.

sw

o

NE

lSOO,

NE NW

~,OO

NNW SSE 100. W

FerÎce'Jua Hit! 600 I -""'"

" -Cu

" V

v

\1 V

;(0 oJ l, I l :\v v

9 v

the ore depasita 1984, structure (d). 1, quariz andesitea a.nd diorites

v II

V

V

\1

v

V

It

v

\1

v

v

SE

Mdaura HIlI

v

.,

V

V

v

y

v " V V

V V

\1 Y

V V

II v

V V

V V

v II

II V

v v y II

_ tQ 2, quartll.

3, Miocene sedimentary rodc.s; 4, sedimentary rodc.s; 5, Jurauic-CretaceoUII ophiolitic rocka; 6-8, hvdrothennal potauic); 9, Au-Ag and base metal mineraliz.a.tionl!l; 10, raulta.

E

V

V

V

\1

V

V

v

\1

v

v

V

NATNE GOLD-BEAIUNG MINERAL ASSEMBLAGES 31

As regards the continuity or discontinuity of the evolution from a porphyry type system to a vein type one, the discussion might be about the presence in the geothermal associations of some relatively "exotic" but frequent minerals, such as graphite. are two variants:

a. In the chemi cal reactions which precipitation, stop the other specific to the porphyry-copper systemj evolution of the metallogenetic process can be continuous but the porphyry system is incompletely de­veloped.

b. Graphite is not a "buffer" mineral, the process is probably discontinuous and the porphyry-copper developed.

Coming back framework of the mineralizations Măgura ore deposits, severa} with other porphyry-copper such as Valea Morii, Musariu Nou (Barza zone) and Muncăceasca-Podul Ionului (Zlatna zone) structures (Fig. 4) can be noted. In all cases the subvolcano occupies a central position within a complex volcanic structure. In case

In the andesitic dome of the Valea Morii structure (Fig. 4 a), the Au-Ag and base metal vein mÎneralizations are formed subsequently to the porphyry-copper- system. The phyllic­argillic alteration related to the vein miner-alizations a propylitic zone which occurs potassic central zone. The metaHic assemblage of the por-phyry type by the presence of pyrite and titaniupl oxides (ru-tile) and as inclusions in chalcopyrite occur as well.

Fericeaua subvolcano in the Muncăceasca­Podul Ionului structure (Fig. 4 c) probably represents an apophysis of the central body which especially penetrates the ophiolitic base-ment and sedimentary deposits, in some cases in the thermal contact zone. metal vein min-eralizations chalcopyrite, bornite, sphalerite, subsequent to the porphyry mÎneralization probably de-veloped at d~pth.

Conclusions

of the Măgura structure the subvolcano has The synthesis of the available mJneralogical, also a relatively , marginally petrographical, and structural bordered by the an desi te . data ore deposit leads necks (Teascu, Mare to several as follows: and Făerag hills) lavas (Fig. a. The and parage-1 B). neses, throughout the vein

In the Musariu Nou strudure (Fig. 4 b) system as well as the relationships observed there are Au-Ag vein mineralizations, domi- among the ore minerals, and between the ore nated by the gold-pyrite-arsenic assemblage, minerals and the gangue ones, indicate a mul­and subordinately common sulphides and tel- tistage and polyascendent circulation regime lurides. They are mainly hosted by the sub- of the geothermal fluids. Thus, native gold was volcanic andesitic rocks with hypogene alter- deposited during at least two stages stressed ation in phyllic-argillic propy- out by the litic fades. The mineraliza- - quartz, tion related to a zone IS tive gold,

the "O" acteristic m absolute height. identification quartz-native of the tellurides in the lower horizons of the arsenopyrite, Măgura subvolcano existing mesothermal similarities. important

arsenopyrite, na­with char-

. parageneses, quartz-native gold­

corresponding to the hypo­domain; the most

concentrationsof native

32

gold, located the in the western of structure, are related to this stage;

- pyrite, Pb, Cu sulphides, Pb, Cu sulphosalts, gold, silver, quartz, baryte; this stage is significant in economic .. ",., ... "".~1- for gold, the and mm-erals constituting the filling of the in the

part the structure. The described association was formed from meso-epithermal solutions which generated a complex characterised by superposed parageneses and telescoping phenomena. N ative gold was de­posited during stage the end of hy­drothermal activity from low-temperature col­loidal solutions.

evolution of was probably discontinuous, the two miner­

. alization stages being delimited in time and space by complex disjunctive tectonic phenom­ena.

The host rock of the Au-Ag vein aHzations is altered in phyllic-argillic fades, the being conatituted of clay minerals, quartz, carbonates, pyrite. Propylitic alterations, by chlorite, carbonates, albite, day minerala, iron VAJIUlI:;O and occur marginaBy.

b. Native gold associated to the of mineralization was deposited from high-alkali solutions. this context, is a met­allotect, stressed out by the presence of this fades in a proximal position versus the opening. The neomineral assemblage charac-teristic of the potassic is by: Ti-bearing biotite, Fe-micas, hydromica, sericite, quartz. In the lower horizons fa-

is partially or totally overprinted by subse­quent alterations, and it can only be detected by chemi cal methods.

c. amphibole andesite which hosts Au-Ag minerala ia consolidated in sub-

VI""" .. "..., body facies. This body penetrates rocks ~f the ophiolitic Miocene posits and andesitic sequences, and occupies a relatively central position in the strudure axis.

Gh. VELCIOV

d. Structural, mi neralogi cal metalloge-netic data point out the existence of a gold porphyry-copper system (dioritic model) the West Măgura subvolcano. At depth, be­neath lowermost level the re-search there might concentrations of eco-

of type, probably related to a potassic zone. similarities with the porphyry-copper little ex-posed by erosion, e.g. Morii,

especially Musariu Nou, are in favour of this idea.

The authors are grateful their "'V"L"'<J>",

Mrs Siko Rozalia Mrs Dinil~ Cristina from Laboratory of Mineralogy of the MINEXFOR

Deva for their help in the microscopic study.

are also due to Mr S. Bo§tinescu and Mr G. Pintea from the Geological tute of Romania for suggestions and opin-lons.

authors are indebted to alI those who contributed to final form of this

References

Berbeleac, 1. (1985) Zăcăminte de aur. Edit. Tehnică, Bucureljti.

Bonham-Jr, H.F. (1984) Three major of ep-ithermal precious metal depasite. Geol. Soc. America ADD. Abstracts with program, 16/6, p. 449.

(1986) Model for volca.nÎc-hasted epithermal precious metal depasits. Volca.nological Congr., Auckland 1986, Symp. Proceedings 5, p. 13-11.

Bol"cO§, M., Berbeleac, 1., Gheol'ghit', Zlmârcă, A., et al. (1980) Studiul met­alogenetic asupra mineralizatiilor hidrotermaJ.e auro-argentifere §i neferoase asociate vulcanismu­lui neogen din Muntii Metaliferi, zona Musariu. Arhiva. MINEXFOR S.A. Deva

, J., Berbeleac, 1. (1984) porphyry copper ore depasits in the Metali­feri Mountains of Transylvania. Unpublished manuscript, Inst. Geai. Geafizică, Bucurefjti.

NATNE GOLD-BEAIUNG MINERAL ASSEMBLAGES 33

Bordea, R., Pop, A. (1989) Studiu mineralogo­petrografic asupra mineralizatiilor auro-argenti­fere interceptate prin lucrări miniere în zona Măcieljul-Măgura-Făerag, Jud. Hunedoara. Arhiva MINEXFOR S.A. Deva.

Bo§tinescu, S. et al. (1981) Sinteza datelor refe-ritoare la disperse din Muntii Metaliferi, prognozei. Arhiva MINEXFOR

(1984) Porphyry Apuseni MountaÎns-RomanÎa. Geojiz. LXIV, p.

the South Inst. Geol.

Ciofiică, G., Jude, R., Uduba§a, G. (1966) Ca­racterele structurale şi mineralogice ale comple­xelor filoniene de la Măgura-Troita (Muntii Met­aliferi). St. cerc. geol., geojiz. geogr., Seria Ge­ologie, 11/2, p. 389-401, Bucureljti.

Petrovskaia, N.V. (1973) Samarodnoe zoloto. Ed. N auka, Moscova.

Sillitae, R.H. (1988) Gold aud silver deposits in porphyry systems. Symp. Bulk Mineable Pre­cious Metal deposits of the Western United States, GeoI. Soc. Nevada, Progr., p. 233-257, Reno.

Udubqa, metalogenetic auro-argentifere şi ne­

neogen din Muntii MINEXFOR S.A. Deva.

- , Bălan, M., Ro§u, E., et aI. (1984) Studiu metalogenetic de sinteză a păr tii de sud. a Muntilor Metaliferi. Arhiva MINEXFOR S.A. Deva.

Vlad, S.N. (1983) Geologia zăcămintelor porphyry copper. Ed. Academiei, Bucureljti.