528 



TABLE 548.— INDEX OF REFRACTION OF SELECTED BIAXIAL MINERALS 



(concluded) 



Biaxial negative minerals (continued) 



Mineral Formula 



Actinolite CaO-3(Mg, Fe)0-4Si0 2 



Wollastonite CaO-Si0 2 



Lazulite (Fe, Mg)0-Al 2 GvP 2 GvH 2 



Danburite CaO-B 2 Gv2Si0 2 



Glaucophane Na 2 0-2FeO-Al 2 Gv6Si0 2 



Andalusite Al 2 Gv Si0 2 



Hornblende Contains Na 2 0, MgO, FeO, Si0 2) etc. 



Datolite 2CaO-2SiGvB 2 GvH 2 



Erythrite 3CoO- As 2 Gv8H 2 



Monticellite CaO-MgO-Si0 2 



Strontianite SrO-C0 2 



Witherite BaO-C0 2 



Aragonite CaO • C0 2 



Axinite 6(Ca, Mn)0-2Al 2 GvB 2 Gv8SiGvH 2 



Dumortierite 8Al 2 GvB 2 Gv6Si0 2 -H 2 



Cyanite A1 2 3 ■ Si0 2 



Epidote 4CaO-3(Al, Fe) 2 Gv6SiGvH 2 



Atacamite 3CuO ■ CuCl 2 ■ 3H 2 



Fayalite 2FeOSi0 2 



Caledonite 2(Pb, Cu)0-SCVH,0 



Malachite 2CuOCCvH 2 



Lanarkite 2PbO-S0 3 



Leadhillite 4PbO-SGv2CGvH 2 



Cerusite PbOCO. 



Laurionite PbCl 2 -PbO-H 2 



Matlockite PbOPbCh 



Baddeleyite . . Zr0 2 



Lepidocrocite Fe 2 GvH 2 



Limonite 2Fe 2 Gv3H 2 in part 



Goethite Fe 2 GvH 2 



Valentinite Sb 2 3 



Turgite 2Fe 2 GvH 2 in part 



Realgar AsS 



Terlinguaite Hg 2 OCl 



Hutchinsonite .... (Tl, Ag) 2 S-PbS-2As 2 S 3 



Stibnite Sb 2 S 3 



Index of refraction 



SMITHSONIAN PHYSICAL TABLES 



