CarndinnMineralogist
Vol.11,pp.514519(1972)
FROMSOMECANADIANOCCURRENCES'SMYTHITE
NICKETIFEROUS
E. H. NICKEL*
Mines Branch, Department of Energg,Mines and Resources,
Ottawa, Canada
Arsrnacr
Nickeliferoussmlthite l(Fe,Ni)3.3Salhas been found in lour Ca4adianlocalities,,go"l"tuJ *i*r Fntlandite *a 111o""i,ii"i,,pyrrhotiteThe nickel content'of.the smythite,*f-rf.n f,* Leur,.io,*d to u"ty betwe3nl.? ;d 7.5% Ni, is consistentlyhigher than thatof the co-existingmonmlinic pyrrhotite'
INrnopucrrox
Smythite was fi15t described by Erd et al. (1957), from an occurrence atBloomington, Indiana, and since that time only a few additional occurrences oF the mineral have been reported : the Kerch Peninsula, U.S.S.R.
(Chukhrov et aI. 1965) I Boron, California (Morgan & Erd 1969) ; andcobalg ontario (Taylor 1970). These few reported occul?ences wouldappear to indicate that smythite is a very rare mineral. However, Taylor
that, tecause of thefibZOl and Nickel & Harris (1971) have suggatedbe much moreactuallymay
pyrrhotite,smythitetomineral's similarity
At the samesuggests.
observations
paucityofreportedthecornmon tlanto(reflectancemicrohardness)andcriteria
preented&
Harristime, Nickel
theSubsequently,
minerals.
twothebetween
distinguiihing
intheassisiauthor has been engaged in an investigation of low-grade nickel deposits
in canada, during the course of which he found an additional four occurrences of smythite which are reported herewith.
SeMprss
1. Lorraine Mine, Gaboury Township, Quebec. The ore is reported tooccur as disseminations, stringers and almost massive forms, at the contactof andcite and gabbro (Kish 1965). The ore samples examined consist
chiefly of pyrrhotite and dralcopyrite in a matnx of quartz, chlorite
calcite, and ieldspar. Other ore minerals in the samples include smythite,pentlandite, violaritg pyrite, marcasitg and magnetite.
Division'" Sulphide Research Contribution No. 37, $geral Sciences* Preserrtaddress: Division of Mineralogy, C.S.I.R.O.,Private Bag, P.O., Wembley'
W.A. 6014,Australia.

NICKELIFEROUS

SMYTHTTE FROM SOME CANADIANOCCURRENCES515

2. Nicopor Mine, 8 miles north of Schreiber, Ontario, on the Canadian
Pacific Railway. The ore @curs along the contact between amphibolite andgranite (Thomson 1957). The samples investigated consist of disseminatedsulphides in a siliceous matrix. The principal ore minerals are pyrrhotite,pyrite, and magnetite ; chalcopyrite, smythite, and violarite are present insmall amounts. Quartz and feldspar comprise most of the gangue minerals
although chlorite, amphibole, and mica are also present.
3. Bird River Mines, (Ore Fault Group Claims, Township 17, Range
15E) in the Lac du Bonnet area of Manitoba. The ore occurs along a fault
zone displacing the Bird River ultrabasic sill. (D. T. Anderson, personalcommunication). The samples used for this study consist of disseminatedto massive sulphides, including pyrrhotitg chalcopyrite, pyrite, sphalerite,
pentlanditg smythite, marcasite, and violarite. The principal non-metallic
minerals are amphibolg quartz and chlorite.
4. Atikokan Iron Mine, Hutchinson Township, Ontario. The ore
occurs in lenses and irregular masses in a highly altered gabbro (Hawley1930). The sample examined consist of a matrix onftalq chlorite, amphibole, and carbonates containing irregular massesof sulphides and magnetite. The sulphide minerals include pyrrhotite, pyrite, chalcopyrite, pentlandite, smythite, and sphalerite.

Mrcnoscoprc OssrnvarroNs
The smythite has a characteristic occurrence in all the samples inwhich it has been found - as flame-like forms in monoclinic pyrrhotite,extending inward from the margins of the pyrrhotite grains (Nickel &Harris 1971) and, where it is particularly abundant, as "flames" within
the pyrrhotite itself (Fig. 1).
The smythite aH'ays has a slightly higher reflectance than the associated pyrrhotite, as pointed out previously by Nickel & Harris (1971)
and can be recognized quite readily in good polished sections. The contrast
can be greatly enhanced by etching with hydriodic acid for about half aminute. This etches the pyrrhotite strongly, but does not appreciably afiectthe smythite (Fig. l).
It should, perhaps, be noted here that the hydriodic acid also etches
monoclinic and hexagonal pyrrhotite difierentially, monoclinic pyrrhotite
being less susceptible to attack than the hexagonal variety (Schwarz &Harris 1970).

516

THE CANADIANIVIINERAL@IST

C.ovrposrnou
The smythite was analyzd. with a Materials Analysis Company(M.A.C.) electron-probe microanalyzer, using synthetic pyrite as a standard for iron and sulphur, and metallic nickel as a standard for nickel.
Corrections were made using Rucklidge's (1967) computer program. The
results of the analyse are shorrn in Table 1.
The analyses in Table I show that the total metal content exceeds
3 atoms per formula in every casg in conformity with observations made onthe Silverfields smythite by Taylor (1970) and by Nickel & Harris (1971).
The nickel content of the smythite exhibits a wide variation, indicating thatnickel can substitute for iron over a c.onsiderable range.
Table 2, which gives the results of nickel analyses made on co-existingsmythite and pyrrhotite, shows that smythite consistently carries morenickel than the co-existing pyrrhotite. The ratio of nickel in smythite tothat in pyrrhotite varies between2.3 and 3.1 in the samples analyzed. TLevalues shown in Table 2 are averagesobtained from a number of deter-Frc. l. Photomicrograph, in oil immersiorq of a polished section from Bird
River Mines, etched with HI. The pyrthotite is etched (grey) and the smythite
is unetched (white). Bla& areas represent gangue minerals and fractures.
Note that the smythite is concentrated around the margins of the pyrrhotite
and along fractures.

NICKELIFEROUS

SMYTHITEFROVI SOME CANADIAN

5I7

OCCURRENCES

rninations. Individual values show a mu& wider spread. For example, thesmythite in Table I with the highest nickel content (7.5%) adjoins
pyrrhotite with 0.8/o nickel, giving a ratio of about 9:1.
Composition of pentlandite ossociated with pyrrhoti'tePentlandite is known to vary in composition, depending on the associated minerals (Graterol & Naldrett 1971). The analyses of pentlandites
frorn the samples containing smtsthite (Table 3) show that all pentlandite
compositions have an Fe:Ni ratio between 0.76 and 0.78, which is appro-Tasu

1. Mrs.opnogr Awerysss or SMvrurrs
Atomic Proportions

Weight Percent

SampleNisFe
Nicopor ming
Schreiber, Ontario
56.8
Bird River mine,
Manitoba
56.3
Atikokan Iron Mine,cAo
Ontario
Iorraine mine,
Ontario (Ave. oi 17) 56.4
Iorraine mine,
Ontario (Max. Ni)
50.9

Fe*NiS

1.74t.l

3264

4000

1.94I,I

3.246

4000

2.84r.2

3.315

4.000

2.2

40.5

3.317

4.000

7.5

40.7

3.nr

4.000

Tdsr-B 2. Drsrnmrrnow or Nrcrpr. BrrwEEN Co-r:asrmc SurrHrra aivo Fynnnorrrs.

Wr /a Ni&el
Smythite
Pyrrhotite

Sample

1.7
r.9
2.8
2.2

Nicopor
Bird River
Atikokan
LorraineRatio
Ni a :Ni
2.8
2.4
2.3

0.6
0.8
120.7J.t

Tesrr 3. CouposmoNs or PsNrLANorrEsAssosarnp wrnr Srvrvrsrrn.
Fe:NiSample
Nicopar
Bird RiverAtikokan
Iorraine

FeNiCo

28.5
26.8

38.3
372
38.2
38.4

0.7

n.8
n.9

:

At, ratio

32.6
33.0
32.3
33.6

0.78
0.76
0.76
u. 1t)

518

THE cANADIANMINEnAL@rsr

ximately in the middle of the pentlandite composition range, and should
be in equilibrium with pyrite below 135oC, according to the tentative phase
diagram propoaed by Graterol & Naldrett (1971).

CoNcrusroNs
Nickeliferous smythite, with a composition approximating (Fe, Ni)B.BSn
apparently exists in equilibrium with monoclinic pyrrhotite and pentlandite
of intermediate composition. The nickel content of smythite consistently
predominates over that of the co-existing pyrrhotite, indicating a greater
tolerance for this element.
Phase equilibrium studies in the synthetic Fe-Ni-S system have so
far not demonstrated the existence of nickeliferous smythite as a stablephase. Since smythite has the appearance of a secondary phase, it may beformed by the late-stage, low-temperature sulphunzatson of monoclinic
pyrrhotite, during which the nickel content becomes re-equilibrated between the two phases. The reason for nickeliferous smythite not having
been found in studies of synthetic systems may be due to the very longtimcs required for it to form at the presumably low temperatures. Experiments are currently underway in these laboratories in attempts to elucidate
the stability relations of the mineral.

AcrxowmncMENTS
The assistanceof D. C. Harris and D. R. Owens, both of the Mineral
SciencesDivision of the Mines Branch, in providing some of the electronprobe analyses is gratefully acknowledged.

RrrrnrNcrs
Cnurnnov, F.Y., Gmlrnr, AD., Sonorrve"S.V. & Vxoveo G,V. (1965): Smythitelrom
Inter. 2, 372-381.
the iron-oredepositsof the KerchPeninsula,Geochem.
Eru, R.C., Evans,H.T. & Rrcrrrn, D.H. (1957): Smythite, a new iron sulphide, andpyrrhotitefrorn Indiana,Arner-Mineral.42, 3@-333.
associatedGnerrnor,M. & NaDnsrr, A.J. (1971): Mineralogyof the MarbridgeNo. 3 and No. 4
equilibration
nickel-ironsulphidedepositswith somecommentson low temperaturein the Fe-Ni-S systerr,Ec. Geol. 66, 886-9m.
Hawrav, l.E. (1930): Geologyof the SapaweLake area,with noteson someiron andgold depositsof Rainy River district, Ontarin Dept. Mina Ann. Rept. 38, pL 6,
1929,l-58.
Krsn,L. (1965)r Geologyof the easthalf of Gabourytownship,QrrcbecDept. Nat. Rer.,
Prelim.Rept.554,

NICKELIFEROUSSMYTHITE FROM SOME CANADIAN OCCURRENCES 5I9
MonsAN, V. & ERD,R.C. (1969) : Minerals of the Kramer borate districq Califomia,Pt, Z Mineral Inform. Serv. (Calif . Diu. Mines Gnl.) 22, 165-172.
Mcrur. E4. & Ilanrrs, D.C. (1971) : Reflecrance and micmhardness of smythite(Fes+xSE),Arner. Mineral. 56, 146+1469.
RucrlDcr, J. (1967) : A computer program for processingmicroprobe data. lotn, GeoI.
75,126.
Scrwanz, EJ. & Hannrs, D.C. (19?0) : Phases in natural pyrrhotite and the efiect oflgatrlS o1 their magnetic properties and composition.l. Geomag Geoelec.!ap.22,
No.4 463-470.
Tavron, L.A. (1970) : smphite, Fe3-p'sa, and associatedminerals from the silverfields
minq Cobalg Ontario. Amer. Mineral, 55, 1650-1658.
THo:vrsor, & (1-957): Copper, nickel, lead and zinc deposits in Ontario, Ont. Dept.
Mines,Metal Re*.Cir.2.
Marutscript receiueilMarch 1971.