Seven New Barium Minerals from Eastern Fresno County, California
THE AMERICAN MINERALOGTST, VOL. s0, MARCH_APRIL, 196s SEVEN NEW BARIUM MINERALS FROM EASTERN FRESNO COUNTY, CALIFORNIA JonN T. Arnons, MBrvrN C. SrrNsoN,RosBnr A. Marrncws, California Division oJ Mines and Geology,San Francisco, CaliJ. and Aoor.n P-lnsr, University of California, Berheley,California. ABSTRACT Seven new barium-bearing silicate minerals have been found in eastern Fresno County, california. The minerals occur in sanbornite-bearing metamorphic rocks which out crop in a narrow zone 2| miles long near a granodiorite contact Macdonaldite(BaCaaSi15O35.1lHzO) is biaxial (- or f), 2V:90", a:1.51g, p:1.524, z:1.530, colorless,X:c,Y:b,Z:a, G(meas.):2.27.It is orthorhombic,Bmmb, B2mb ot Bm2yb,a:74.06, b:23.52, e:73.08, Z:4. Krauskopfite (BaSizOs.3HzO) is biaxial (-), 2V:88o, a:1.574, p:l5g7, t:1.599, colorless, X:b, Y,ta:6", ZAc:lO|", atrc:94o 32,, G(meas.):3.14. It is monoclinic, P 2r/ a, a : 8.460,b : 10.622,c : 7.837, p : g4o 32t, Z : 4. Walstromite (BaCazSi:O) is biaxial (-), 2V:30", a:1.668, p:.1.684, z:1.685, colorless,G(meas.):3.67. It is triclinic, PI or Pl, a :6.743, b:9.607, : c 6.687,q:69" 5l', 0 : 702" 14',7 :97o 6+', Z:2. Fresnoite (Ba:TiSizOs)is uniaxial (-), a:1.775, e:1.765,0:colorlessi B:yellow, G(meas.):4.43. It is tetragonal, P4/mbm, P4bm, or P4b2, a:8.52, c:5.21O, Z:2.
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