527 



TABLE 548.— INDEX OF REFRACTION OF SELECTED BIAXIAL MINERALS 



(continued) 



Biaxial positive minerals (continued) 



Mineral Formula 



Olivenite 4CuO-As 2 GvH 2 



Anglesite PbO-SO, 



Titanite CaO-TiGvSiO, 



Claudetite As 2 3 



Sulfur S 



Cotunnite PbCl 2 



Huebnerite MnO • WOs 



Manganite Mn 2 3 ■ H 2 



Raspite PbOVVO, 



Mendipite 2PbO-PbCl 2 



Tantalite (Fe, Mn)0-Ta 2 5 



Wolframite (Fe, Mn)0-WO, 



Crocoite PbO-Cr0 3 



Pseudobrookite . . . 2Fe 2 Gv3Ti0 2 



Stibiotantalite Sb 2 GvTa 2 5 



Montroydite HgO 



Brookite Ti0 2 



Massicot PbO 



Biaxial negative minerals 



Mirabilite Na 2 O-SGvl0H 2 O 



Thomsenolite .... NaF-CaF 2 - A1F 3 -H 2 



Natron Na,O-CGvl0H 2 O 



Kalinite K,0-A1,CV4SCV24H,0 



Epsomite MgO-SGv7H 2 



Sassolite B 2 GvH 2 



Borax Na 2 O-2B 2 Gvl0H 2 O 



Goslarite ZnO-SGv7H 2 



Pickeringite MgO- Al 2 Gv4SGv22H 2 



Bloedite Na 2 0-MgO-2SGv4H 2 



Trona 3Na 2 0-4CGv5H 2 



Thermonatrite ... Na 2 0-CGvH 2 



Stilbite (Ca, Na 2 )0-Al 2 Gv6SiGv5H 2 



Niter K 2 0-N 2 5 



Kainite MgO-SGvKCl-3H 2 



Gaylussite Na 2 0-CaO-2CGv5H 2 



Scolecite CaO- Al 2 Gv3SiGv3H 2 



Laumontite CaO-Al 2 Gv4Si0 2 -H 2 



Orthoclase K,0- Al 2 Gv6Si0 2 



Microcline Same as preceding 



Anorthoclase (Na, K),0-ALCV6SiO, 



Glauberite Na 2 0-CaO-2S0 3 



Cordierite 4(Mg, Fe)O-4Al 2 Gvl0SiGvH 2 O 



Chalcanthite CuO-SGv5H 2 



Oligoclase Ab«An 



Beryllonite Na 2 0-2BeO-P 2 5 



Kaolinite Al 2 Gv2SiGv2H 2 



Biotite K 2 0-4(Mg, Fe)0-2Al 2 Gv6SiGvH 2 



Autunite CaO-2UGvP 2 Gv8H 2 



Anorthite "An" = CaO- Al 2 3 -2Si0 2 



Lanthanite La 2 Gv3CGv9H 2 



Pyrophyllite Al 2 Gv4SiGvH 2 



Talc 3MgO-4Si0 2 -H 2 



Hopeite 3ZnO-P 2 Gv4H 2 



Muscovite K 2 0- Al 2 3 -6Si0 2 -2H 2 



Amblygonite Al 2 3 -P 2 5 -2LiF 



Lepidolite Al 2 Gv3SiGv2(K, Li)F 



Phlogopite K 2 0-6MgO-Al 2 Gv6SiGv2H 2 



Tremolite CaO-3MgO-4Si0 2 



(continued) 



SMITHSONIAN PHYSICAL TABLES 



