Tun Au ERTcANM TNERALocIsT JOURNAL OF THE MINERALOGICAL SOCIETY OF AMERICA

Vol.40 JULY-AUGUST,1955 Nos. 7 and 8

HAWLEYITE, ISOMETRIC SULPHIDE, A NEW MINERAL*

R. J. Tnanr aNo R. W. Bovro, GeologicalSuraey oJ Canada, Ottowa. Assrnecr

A new mineral identical with isometrjc cadmium sulphide has been found in the Hector- calumet mine, Galena Hill, Yukon Territory. The mineral occurs as a fine-grained, bright yellow, earthy coating on and , in vugs and along late fractures. Geo- chemical and mineralogical evidence, together with laboratory studies, suggest that the mineral has been

h.rrnooucrroN In 1954, while investigating the lead-zinc-silver deposits in the Keno- Galena Hill area of the Yukon one of the authors (R.w.B.) collected a specimen of sphalerite richly coated with a bright yellow mineral. The specimenwas submitted to the X-ray Laboratory, GeologicalSurvey of Canada,for identification of the yellow mineral. The r-ray powder pattern of the mineral was found to match the pat- tern of B-CdS,the isometric polymorph of cadmium sulphide.A survey of the literature revealedthat this compound has not been reported as occurringin nature. professor The new mineral is named hawleyite in honor of J. E. Hawley of Queen'sUniversity, Kingston, Ontario, who has contributed greatly to Canadian as a mineralogistand teacher.

IleNrrnrcerrow (R.J.T.) The specimen consists of a mixture of massive siderite and coarsely- crystalline sphalerite, with a bright yellow coating. A microscopic exami- nation revealed that the coating was composedof a bright yellow mineral, * Published by permission of the Deputy Minister, Department of Mines and rechnical Surveys, Ottawa.

J.).) 550 R. J. fRAiLL AND R. W' BOTLE now named hawleyite, admixed with lesser amounts of fine-grained sphaleriteand siderite.The grain-sizeof the hawleyite was so small that individual grains could not be discerned. Someof the admixed sphaleriteand sideritewas removedby brushing the coatingthrough a 325-meshscreen' but a sampleof hawleyitesuitable for quantitative chemical analysis and specifi.c-gravity determination could not be obtained. A partly purified sample was analyzed semi- quantitatively by r-ray spectrography and found to contain 50-70 per cent cadmium, 5-10 per cent zinc, and lessthan 5 per cent iron. Selenium could not be detected,indicating that lessthan 0.05 per cent is present. Several *-ray powder photographs of hawleyite were taken using a camera with a diameter of 57.54 mm., and nickel-filteredcopper radi-

T-q.nr-n1. Hawr-rvrtn, p-CdS; X-R.qv?omrn P.q.:rrrxx IsometricF43m; a:5.818 A, Z:4

(calc) 1 (Cu) d (meas) d (calc) I (Cu) d (meas) d

10 3.s6A 111 3.364 1.2e8A 420 1.301A ^ 2.90 200 2.9r 1.186 422 1.188 8 2.058 220 2.O57 t.t20 333,511 1.r20 1.028 6 I. /JJ Jll l - /J+ 1 028 440 1 1.680 222 1.680 0 .985 531 0.983 2 r.453 400 r.454 0.918 620 0.920 0.887 1.338 JJI I . J.tJ 0.887 533

ation. The observedintensities and measuredspacings of the hawleyite pattern are listed in Table 1,-togetherwith the spacingscalculated from a lattice constant of 5.818 A. T.t'r. observedintensities and measured spacingsof the r-ray patterns of artificial B-CdS published by Milligan flSS+l and Ulrich & Zachariasen (1925) are reproduced in Table 2. The closeagreement between the patterns of Tables I and 2 clearly establishes the identity of the natural and artificial materials. Hawleyite has a sphalerite-type structure with space gtoup F43m' The lattice constant,o:5.818* 0.005A, was calculatedfrom the powder pattern. Assuminga cell content of 4[CdS],the caiculatedspecific gravity of the mineral is 4.87.

OccunnnNco (R.W.B.) The Hector-Calumet mine, from which the hawleyite was obtained, is the largest and most productive of the lead-zinc-silver mines in the Keno-Galena Hill area, Yukon Territory. This mineral district is in the central Yukon 35 miles northeast of Mayo and some 220 miles due north HAW LEYITE, ISOMETRIC CADMIUM SULPHIDE 557

Trsr'n 2. Anrnrcrel €-CdS; X-Rev Powlrn parmnx IsometricF43m: a:5.820 A. Z:+

Ulrich & Zachariasen(1925) (Milligan 1934)

1 (Cu) 1 (Cu) d (meas)

5 3.3sA 111 10 3.364 1 2.93 200 3 2.90 5 2.062 220 10 2.06 5 1.758 Jll 9 1.756 L_1 2L 1.683 222 1 1.683 1 1.452 400 1 1.456 a aL L-L' I.JJ' 331 z I . JJ.)

17 tt 1.303 420 1 1.302 nl LZ 7.197 422 1.189 ol -2 1.122 333,511 J 1.121 2 1.033 MO 2 1.026 s+ 0 985 531 a o.982 1 0.971 442,600 o1 .d o.922 620 1+ 0.888 533 1 o.879 622

1 Spacings calculated from the g values of Ulrich & Zachariasen. of whitehorse. The district is servedby an all weatherroad from white- horseand by Canadian Pacific Airlines. The consolidated rocks underlying the area are mainry sediments belongingto the Yukon group of precambrian or paleozoicage. They consistof sericitic,chloritic, and graphitic schists,phyllites, and quartz_ ites. conformable sills and lensesof greenstoneoccur throughout the sediments. The lead-zinc-silvervein depositsof Keno and GarenaHills occur in brecciatedfault zonesand sheetedzones. Two types of veins are recog- nized; an early vein type consistingof quartz, pyrite, and arsenopyrite, and a late vein type mineralized with siderite, galena, sphalerite, and argentian tetrahedrite. Both types may occur separately. The early type, however, may be fractured and contain minerals of the secondtype. The veins near the surface are highly oxidized. The depth of oxidation varies but is seldom less than 50 feet. The minerals found in the oxidized zone include limonite, various manganese oxides, calcite, gypsum, smithsonite, cerussite, anglesite, quartz, azurite, malachite, and oxid.es of arsenic and antimony. A marked feature of the veins in both the primary and oxidized parts, 558 R. T. TRAILL AND R. W. BOYLE is the presence of numerous vugs and open spaces in which excellent crystals of galena, sphalerite, siderite, calcite, gypsum' and quartz abound.

' ' oRrGrN The geochemistry of the veins has not been worked out in detail but the mode of occurrenceof the hawleyite suggeststhat it is a secondary mineral which has been deposited from meteoric waters in vugs and along late fractures. Geochemicalwork shows that the sphalerite in the veins contains up

to limonite by the meteoric waters with consequent solution and trans- port of the zinc and probably the cadmium as sulphates' Laboratory studies on the precipitation of cadmium sulphide from solutions of cadmium salts have been made by several investigators, and their results have a direct bearing on the origin of the hawleyite. Thus, Biihm & Niclassen (Ig24) first showed by r-tay difiraction that p-CdS is

agonalpolymorph, a-CdS, by heating P-CdSin sulphur vapor' Milligan (iSS+)showed that g-CdS is formed at 30oC. when HzSis passedthrough a 0.1 N solutionof cadmium sulphate made acid by the addition of 1 c. c. of cencentrated H2SOato 50 c' c. of solution. Milligan also found that HAWLEYITE, ISOMETRIC CADMIUM SULPHIDE 559 d-CdS is produced from 0.1 N solutions of cadmium nitrate, chloride, bromide, and iodide when treated in the samemanner. Theselaboratory studies indicate clearly that hawleyite is the polymorpb of cadmium sulphide which will be precipitated under reducing conditions from acidic sulphate solutions. Considering the field facts and the knowledge that cadmium follows zinc closelyin its geochemistry,it is logical to assumethat in the zone of oxidation cadmium would be taken into solution by the meteoric waters which contain H2SOa,and be transported downward into the zone oI reduction. HzS, generated by the action of HzSO+on primary sphalerite and other sulphides, would reduce the cadmium sulphate and precipitate hawleyite (B-CdS) as shown by the laboratory studies. Acidic sulphate solutions, from which the hawleyite polymorph of cadmium sulphideprecipitates, are common in sulphide deposits,and it seems probable that hawleyite is more common than its very recent discovery would indicate. Much material, previously identified as greenockite by casual hand-specimenexamination, may prove to be hawleyite when identified by r-ray diffraction.

RrrnnBNcns

BriHu, J. & Nrcr,rssnx, H. (1924) : Uber amorphe Niederschllige und Sole, Zeits, anorg. Chem.,l32,7. Dawa, J. D. & E. S. (1944): Systemof Mineralogy,l, ed. 7, by C. palache, H. Berman and C. Frondel, New York. Mru,rclN, W. O. (1934): The color and of precipitated cadmium sul- phide, -r. Phys. Chem.,38, 797-800. urnrcn, F. & ZecnanrasrN, w. (1925): uber die Kristallstruktur des a- und 0-cds sowie des Wurtzits, Zeits. Krist., 62, 2ffi-27 3.