TABLE 407 (Concluded) 

 INDEX OF REFRACTION 

 Selected Biaxial Minerals 



369 



Mineral. 



Formula. 



Index of refraction. 



(b) Biaxial Negative Crystals (continued). 



Beryllonite. . . 

 Kaolinite .... 



Butite 



Autunite 



Anorthite. . . . 

 Lanthanite. . . 

 Pyrophyllite . 



Talc 



Hopeite 



Muscovite 

 Amblygonite . 



Lepidolite 



Phlogopite. . . 

 Tremolite. 



Actinolite 



Wollastonite . 



Lazulite 



Danburite 

 Glaucophanite 

 Andalusite. . . 

 Hornblende . . . 



Datolite 



Erythrite 



Monticellite. . 

 Strontianite. . . 



Witherite 



Aragonite 



Axinite 



Dumortierite. 



Cyanite 



Epidote 



Atacamite 



Fayalite 



Caledonite. . . 



Malachite 



Lanarkite 



Leadhillite. . . 



Cerussite 



Laurionite 

 Matlockite. . . . 

 Baddeleyite . . 

 Lepidocrocite. 



Limonite 



Goethite 



Valentinite... 



Turgite 



Realgar 



Terlinguaite. . 

 Hutchinsonite . 

 Stibnite 



Na2O.2BeO.P2O5 



Al2O3.2SiO2.2H2O 



K 2 0.4(Mg, Fe)0. 2Al2O3.6SiO2.H2O 



CaO.2UO3.P2O5.8H2O 



"An" = CaO.Al 2 03.2Si02 



La2O3.3CO2.9H2O 



Al2O3.4SiO2.H2O 



3MgO.4SiO2.H2O 



3ZnO.P2O5.4H2O 



K2O.3Al2O3.6SiO2.2H2O 



Al2O3.P2O5.2LiF 



Al 2 03.3Si0 2 .2(K, Li)F 



K2O.6MgO.Al2O3.6SiO2.2H2O 



Ca0.3Mg0.4Si0 2 



Ca0.3(Mg,Fe)0.4Si0 2 



CaOSi0 2 



(Fe, Mg)O.Al 2 03.P20 5 .H20 



CaO.B 2 03.2Si0 2 



Na 2 0.2FeO.Al203.6Si02 



Al 2 a.Si02 



Contains Na 2 0, MgO, FeO, SiO:, etc. 



2CaO.2SiO2.B2O3.H2O 



3CoO.As2O5.8H2O 



CaO.MgO.SiO2 



SrO.C0 2 



BaO.C0 2 



CaOC0 2 



6(Ca, Mn)0.2Al 2 03.B203.8Si02.H 2 



8Al2O3.B2O3.6SiO2.H2O 



Al 2 03.Si02 



4 Ca0.3(Al, Fe) 2 03.6Si02.H 2 



3CuO.CuCl2.3H2O 



2FeO.Si0 2 



2fPb.Cu)O.S03.H20 



2CuO.CO2.H2O 



2PbO.S0 3 



4PbOSO3.2CO2.H2O 



PbO.C0 2 



PbCl2.PbO.H2O 



PbO.PbCU 



Zr0 2 



Fe203.H 2 



2Fe203.3H 2 O in part 



Fe 2 03.H20 



Sb 2 03 



2Fe203.H2O in part 



AsS 



Hg 2 OCl 



(Tl, Ag)2S.PbS.2As2S 3 



SbjSs 



•552 

 .561 



• S4i 

 •553 



• 576 

 .520 



• 552 

 •539 



• 572 

 .561 



• 579 

 .560 



• 562 

 .609 

 .611 

 .616 

 .603 

 .632 

 .621 

 .632 

 .629 

 .625 

 .626 

 .651 

 .520 

 •529 



• 531 

 .678 

 .678 

 . 712 

 •729 

 .831 

 .824 

 .818 

 .655 

 ■930 

 .870 

 .804 



2.077 

 2.040 

 2.130 

 1.930 

 2. 170 

 2.210 

 2.180 

 2.450 

 2.460 

 2-3SO 

 3.078 

 3-194 



558 

 563 

 574 

 575 

 S84 

 587 



59° 

 59° 

 593 

 59S 

 606 

 623 

 627 

 629 

 632 

 634 

 638 

 638 

 642 

 653 

 661 

 662 

 667 

 676 

 682 

 68s 

 686 

 720 



754 



861 



864 



866 



875 



990 



2.000 



2.076 



2. 116 



2.150 



2.190 



2. 210 



2.290 



2-35° 



2.350 



2.550 



2 . 590 



2.640 



3176 



4-303 



S61 

 56s 

 574 

 577 

 588 

 613 

 600 

 589 

 590 

 594 

 597 

 605 

 606 

 635 

 636 

 631 

 639 

 636 

 638 

 643 

 653 

 669 

 6gg 

 668 

 667 

 677 



689 



728 



768 



880 



874 



909 



909 



020 



010 



078 



158 



150 



200 



510 



310 



350 (Li) 



350 



550 (Li) 



610 (Li) 



670 (Li) 



188 



460 



Smithsonian Tables. 



