MTNERAT.OGTCALNOTES ll43 batchesof CoCOa,NiCO3 and MgCOr were treated in a furnace at 110o C. under approximately 1 atmosphereof COz for 3 hours before weigh- ing. Equimolar mixtures of four combinations in the systems BaCOa- MnCOa, BaCOrNiCOs, BaCOr-CoCOa,and BaCOTMgCO3w€r€ care- fully prepared by grinding in alcohol in an agate mortar. Experiments were carriedout at 500" C. and 15 kilobars in a squeezerdevice (Griggs and Kennedy, 1956, 1956) for a period of 25 hours. Samples were quenched and examined by r-ray diffraction. The results show that 1:1 binary compoundsare formed in the sys- tems BaCO3-MnCOaand BaCOa-MgCOr. A comparison of the c-ray diffraction data of natural norsethite and the synthetic MgBa(CO3), compound is given in the first and second columns of Table 1' The agreementis fair. The interplanar spacings and *-ray diffraction intensities obtained from the synthetic MnBa(COa)zmake it obvious that this compoundis isostructural with norsethite,and calcite-likein structure. These r-ray data are listed in the third coiumn of Tabie 1. Similar compounds of BaCOs with CoCOa and NiCOa were not ob- servedto form under the conditionsof theseexperiments. The writer is indebted to ProfessorJulian R. Goldsmith for his en- couragementand interest.

RBlnnrNcns

Cnmrc, L. L. Y. (1964) Subsolidus phase relations in the systems BaCOs-SrCOr, SrCOr CaCO3,and BaCOrCaCOa. Jour. Geol"(in press) Gnrccs, D. T. .lNo G. C. KeNNruv (1956) A simple apparatus for high pressures and tem- peratures. Am. I our. Sei. 254, 7Z2-7 35. Mnosn, M. E., E. T. Cneo, J. J. Fennv mto C. Mrr.roN (1961) Norsethite, BaMg(CO:)z' a new mineral from the Green River formation, Wyoming. Am. Mineral'.4q 42M29. Prlecnr, C., H. BBnnlN eNo c. FnoNoel (1951) TheSltstem oJ Mineralogy,Ttheil.,vol. II,132-221. John Wiley & Sons,New York.

THE AMERICAN MINERALOGIST, VOL. 49' JIILY-AUGUST' 1964

A NEW OCCURRENCEOF SroNnv A. Wrr-r-relrs,Silaer Ki'ng Mines, Inc', Ely, I{eaada.

Langite, Cua(SOa)(OH)o' HrO (?), has beenfound in a complexsuite of supergenelead and minerals occurring in the Caroline tunnel of the Ward mine, about 18 miles south of Ely, Nevada. Langite occurs as minute crystals which coat superficially altered in a qrartz gangue. Other hypogene in the ores in- clude ,, , and hessite.Incipient oxidation of the lIM MINERALOGICALNOTES

chalcopyrite has turned the surface of the crystals to an earthy mixture of sooty chalcocite,coveilite, and goethite, and much of the rangite oc- curs in such material. Among the other supergeneminerals present, bro- chantite and are the earliest to crystallize. These are followed by approximately contemporaneousserpierite (Cu,Zn,Ca)s(S04)r(OH)6 .-3HlO (?),langite and . Langite and serpieritemay be replacedby devillite, Cu+Ca(SODz(OH)u. 3HzO; the replacementis contemporaneous with the beginningof alteration of sphalerite.other speciesfound in the assemblageinclude , greenockite, wire silver and paratellurite. The closerelation between langite and chalcopyrite is similar to that de- scribedby Pierrot and Sainfeldat Mollau, Haut-Rhin (1959). Although the langite crystals are small (up to 5 mm) they are eminently suited for morphological study. The larger crystals, which are generally a fine sky-bluecolor, are often twinned repeatedlyon [ 110]. The twins are tabular or scaly on {001} and occur as crustson chalcopyrite. smaller crystals are generally untwinned and are brue-green. These crystals are elongateon {100} and may occur in parallel growth with of similar habit. In such casesthe crystals are ioined on a common{001}. Examination of a number of langite crystals on the two-circre goniom- eter showedthe following forms: {001} c, {010} b, [120] n, {110} m, {021} f, {102} t, and l24l } p. Serpieriteof similarhabit showedthefol- Iowingforms: {001}, {0101, {110}, I2t0l, and {112}.Two langitecrys- tals are shown in Fig. 1. The upper one is typical of the smalr, blue-green crystals and the lower, twinned crystal is typical of the larger, sky-blue crystals. The optical orientation is as reported by other workers, ,i.e.X:c, Y: D,and Z: a. Absorptionis in blue with Y> Z> X. Other optical propertiesof the langite are tabulated below:

sky-bluecrystals blue-greencrystals a:1.641+.002 a:1.641+.002 0:1.690+.001 p:1.690+.001 t:1.712+.001 z: 1.705+ .001 a-a:,077 7-a:.064 2V(calc):66" 2V(calc):560

The blue-green crystals give a faint microchemical reaction lor zinc whereasthe zinc content of the sky-bluecrystals is below the limits of de- tection. The devillite gives a strong zinc test and the serpierite is vir- tually zinc-free. Identification of the langite was confirmed by an c-ray powder pattern MINERALOGICAL NOTES 1145

twinon (llO)

Frc. 1. Langite crystals. which have good agreementwith data publishedby Pierrot and Sainfeld. Devillite and serpieritewere identified on the basisof morphology,optics, and microchemical tests. X-ray powder data on authenticated, type local- ity specimensof these speciesare unavailable. RrnnnoNcr

Prrnrorr, R .q,NoP. SnrNrrID (1958) Sur la langite des vosges. Bul.l. soc. Franc. M'ineraL. 8t,257,260.