368 



TABLE 407 (continued) 



INDEX OF REFRACTION 



Selected Biaxial Minerals 



Mineral. 



Index of refraction. 



Formula. 



(a) Biaxial Positive Minerals (continued). 



Zoisite 



Strengite 



Diasporite 



Staurolite 



Chrysoberyl. . . 



Azurite 



Scorodite 



Olivenite 



Anglesite 



Titanite 



Claudetite .... 



Sulfur 



Cotunnite 



Huebnerite. . . . 

 Manganite. . . . 



Raspite 



Mendipite 



Tantalite 



Wolframite . . . 



Crocoite 



Pseudobrookite 

 Stibiotantalite. 

 Montroydite . . 



Brookite 



Lithargite 



4CaO.3Al2O3.6SiO2.H2O 



Fe2O3.P2O5.4H2O 



AI2O3.H2O 



2FeO.5Al2O3.4SiO2.H2O 



BeO.AhOs 



3CuO.2CO2.H2O 



Fe2O3.As2O5.4H2O 



4CuO.As2O5.H2O 



PbO.SOs 



CaO.TiO2.SiO2 



AS2O3 



s 



PbCb 



MnO.WOs 



Mn 2 O).H20 



PbO.WOs 



2PbO.PbCl 2 



(Fe, Mn)0.Ta20s 



(Fe, Mn)0.WOi 



PbO.CrC* 



2Fe203.3Ti02 



Sb 2 03.Ta 2 05 



HgO 



Ti0 2 



PbO 



1 . 700 

 1 . 710 



1 . 702 

 1-730 

 1-747 

 I- 730 

 I -765 

 1.772 

 I.877 

 1. 000 

 1. 871 

 I-05C 



2. 200 

 2. 170 

 2.240 

 2.270 

 2.240 

 2. 260 

 2.310 

 2.310 

 2.380 

 2-374 

 2.370 

 2.583 

 2.510 



1.702 

 1. 710 

 1. 722 



1. 741 

 1.748 

 1.758 

 1-774 

 1. 810 

 1.882 

 1.907 

 1.920 

 2.043 



2. 217 

 2. 220 

 2. 240 

 2. 270 

 2. 270 

 2.320 

 2.360 

 2.370 

 2.390 

 2.404 

 2500 

 2.586 

 2. 6lO 



I.706 



1-745 



I.750 



1.746 



1-757 



1.838 



1-797 



1.863 



1.894 



2.034 



2.010 



2. 240 



2. 260 



2.320 



2.530 (Li) 



2.300 



2.310 



2.430 (Li) 



2.460 (Li) 



2 . 660 (Li) 



2.420 (Li) 



2-457 



2.650 (Li) 



2.741 



(b) Biaxial Negative Minerals. 



Mirabilite 



Thomsenolite. . 



Natron 



Kalinite 



Epsomite 



Sassolite 



Borax 



Goslarite 



Pickeringite. . . 



Bloedite 



Trona 



Thermonatrite 



Stilbite 



Niter 



Kainite 



Gaylussite 



Scolecite 



Laumontite . . . 

 Orthoclase . . . 

 Microcline 

 Anorthoclase . . 

 Glauberite 



Cordierite 



Chalcanthite . . 

 Oligoclase 



Na20.S03.ioH 2 



NaF.CaF2.AlF3.H2O 



Na 2 O.C0 2 .ioH20 



K2O.AI2O3.4SO3.24H2O 



MgO.SO3.7H2O 



B2O3.H2O 



Na 2 0.2B 2 03.ioH20 



ZnO.SO3.7H2O 



MgO.Al 2 3 .4S03.22H20 



Na2O.MgO.2SO3.4H2O 



3Na2O.4CO2.5H2O 



Na2O.CO2.H2O 



(Ca, Na2)O.Al 2 03.6Si02.5ll20 



K2O.N2O5 



MgO.SO3.KCl.3H2O 



Na2O.CaO.2CO2.5H2O 



CaO.Al2O3.3SiO2.3H2O 



CaO.AUO3.4SiO2.4H2O 



K 2 O.Al 2 03.6Si02 



Same as preceding 



(Na, K) 2 O.Al203.6Si02 



Na2O.CaO.2SO3 



4(Mg, Fe)0. 4 Al203.ioSi0 2 .H20 



CuO.SO3.5H2O 



Ab«An 



1-394 

 1.407 

 1-405 

 1 -430 

 1-433 

 1 -340 

 1-447 

 1-457 

 1.476 

 1.486 

 1 .410 

 1.420 

 1.494 

 1-334 

 1.494 

 1.444 



1. 512 



1. 513 

 1. 518 

 1.522 

 1-523 

 I-5I5 

 1-534 

 I. 516 

 1-539 



.398 



• 415 



• 440 



• 458 



.461 

 •459 

 •472 

 .484 

 483 

 ■489 

 -542 

 .518 

 .500 



• 506 

 .516 



• 523 

 ■519 

 •525 



526 

 ■530 

 -531 



536 

 -540 

 ■546 

 ■547 



Smithsonian Tables. 



