MCALPINEITE, CU3TEO6.H2O, A NEW MINERAL FROM THE MCALPINE MINE, TUOLUMNE COUNTRY, CALIFORNIA, AND FROM THE CENTENNIAL-EUREKA MINE, JUAB COUNTY, UTAH

Mcalpineite, ideally Cu3TeO6.H2O, occurs as isolated 0.5 mm-sized emer ald green cryptocrystalline crusts on white quartz at the long-abandon ed McAlpine mine, Tuolumne County, California, U.S.A. Associated nonme tallic phases are muscovite (mariposite), calcite, goethite, hematite, chlorargyrite, choloalite, keystoneite, mimetite, malachite, azurite, annabergite and a host of unidentified crusts, both crystalline and a morphous. Associated metallic minerals include pyrite, acanthite, hess ite, electrum, altaite, native silver, galena, pyrargyrite, sphalerite and owyheeite. The mineral has also been identified at the Centennial Eureka mine, Juab County, Utah, U.S.A., where it occurs as interstiti al olive-green coatings and as millimetre-sized dark green-black crypt ocrystalline nodules lining drusy quartz vugs. Associated minerals are xocomecatlite, hinsdalite-svanbergite, geothite and several new speci es including two hydrated copper tellurates, a hydrated copper-zinc te llurate/tellurite, and a hydrated copper-zinc tellurate/tellurite-arse nate-chloride. Mcalpineite is cubic, P-lattice (space group unknown), a = 9.555(2) angstrom, V = 872.4(4) angstrom. The strongest six lines in the X-ray powder-diffraction pattern [d in angstrom (I) (hkl)] are: 4.26(40)(210), 2.763(100)(222), 2.384(70)(400), 1.873(40)(431,510), 1 .689(80)(440) and 1.440(60)(622). The average of four electron-micropr obe analyses (McAlpine mine) is CuO 50.84, NiO 0.17, PbO 4.68, SiO2 0. 65, TeO3 39.05, H2O (calc.) [4.51], total [100.00] wt. %. With O = 7, the empirical formula is .01)SIGMA2.89(Te0.97Si0.05)SIGMA1.02O5.90.1.1 0H2O. This gives a calculated density of 6.65. g/cm3 for Z = 8. The av erage of two electron-microprobe analyses (Centennial Eureka mine) is CuO 51.2, ZnO 3.1, TeO3 39.0, SiO2 0.2, As2O5 0.8, H2O (by CHN element al analyser) 7, total 101.3 wt. %, leading to the empirical formula (C u2.56Zn0.15)SIGMA2.71 (Te0.88Si0.02As0.02)SIGMA0.92O5.47.1.53H2O. The infrared absorption spectrum shows definite bands for structural H2O w ith an O-H stretching frequency centred at 3320 cm-1 and a H-O-H flexi ng frequency centred at 1600 cm-1. In reflected light Mcalpineite is i sotropic, nondescript grey, with ubiquitous brilliant apple to lime gr een internal reflections. The refractive index calculated from Fresnel equations is 2.01. Measured reflectance values in air and in oil are tabulated. Reflectance study also shows that cryptocrystalline aggrega tes are composed of micron-sized sheaves of fibrous or prismatic cryst als. Other physical properties include: adamantine lustre; light green streak; brittle; uneven fracture; translucent to transparent and nonf luorescent under both long- and short-wave ultraviolet light. The name is for the first known locality, the McAlpine mine.