286 



Table S4S. 



INDEX OF REFRACTION. 

 Selected Biaxial Minerals. 



The values are arranged in the order of increasing index of refraction and are for the sodium D line except where 

 noted. Selected by Dr. Edgar T. Wherry from private compilation of Dr. Esper S. Larsen of the U. S. Geological 

 Survey. 



Mineral. 



Formula. 



Index of refraction. 



«/3 



(a) Biaxial Positive Minerals. 



Stereorite 



Aluminite 



Tridymite 



Thenardite 



Camallite 



Alunogenite. . . . 

 Melanterite .... 



Natrolite 



Arcanite 



Struvite 



Heulandite 



Thomsonite .... 

 Harmotomite. . . 



Petalite 



Monetite 



Newberyite .... 



Gypsum 



Mascagnite . . . . 



Albite 



Hydromagnesite 



Wavellite 



Kieserite 



Copiapite 



Whewellite 



Variscite 



Labradorite . . . . 



Gibbsite 



Wagnerite 



Anhydrite 



Colemanite 



Fremontite 



Vivianite 



Pectolite 



Calamine 



Chondrodite 



Turquois 



Topaz 



Celestite 



Prehnite 



Barite 



Anthophyllite . . 



Sillimanite 



Forsterite 



Enstatite 



Euclasite 



Triplite 



Spodumenite . . . 



Diopside 



Olivine 



Triphylite 



NajO. (NH4)20.Ps06.9H20 

 AI2O3.SO3.9H2O 



Si02 



NazO.SOa 



KCl.MgCl2.6HjO 



AI2O3.3SO3.16H2O 



FeO.SO3.7H2O 



Na2O.Al2O3.3SiO2.2H2O 



K2O.SO3 



(NH4)20.2MgO.P205.I2H20 



CaO.Al2O3.6SiO2.3H2O 



(Na2, Ca)O.Al203.2Si02.3H20 



(K2, Ba)O.A]203.sSi02.oH20 



Li-20.Al203.8Si02 



2CaO.P2Os.H2O 



2MgO.P2O6.7H2O 



CaO.SO3.2H2O 



fNH4)20.S03 



"Ab" = Na2O.Al203.6Si02 

 4MgO.3CO2.4H2O 



3Al203.2P206.I2fH20, 2HF) 



Mgo.so3.H20 



2Fe203.5S03.i8H20 



cao.c203.H20 

 A1203.P206.4H20 



Ab2An3 



AI2O3.3H2O 



3MgO.P2O6.MgF2 



CaO.SOs 



2CaO.3B2O3.sH2O 



Na20.Al203.P206.(H20, 2HF) 



3FeO.P20i,.8H20 



Na2O.4CaO.6SiO2.H2O 



2ZnO.SiO2.H2O 



4Mg0.2Si02.Mg(F, 0H)2 



CuO.3Al2O3.2P2O5.9H2O 



2A10F.Si02 



SrO.SOs 



2CaO.Al2O3.3SiO2.H2O 



BaO.SOa 



MgO.SiOa 



Al203.Si02 



2MgO.Si02 



MgO.Si02 



2BeO.Al2O3.2SiO2.H2O 



3MnO.P2O5.MnF2 



Li20.Al203.4Si02 



CaO.Mg0.2Si02 



2(Mg, Fe)0.Si02 



Li20.2(Fe, Mn)O.P206 



• 469 

 .470 



• 473 

 •48s 

 •494 



• 483 

 .486 



• 493 

 •497 

 •504 

 •50s 



• 52s 

 .508 

 .516 

 •52s 



■ 533 

 •530 



• 533 



• 536 



• 540 

 ■552 



■ S86 



• 595 



■ 650 



■ 582 



■ 568 

 .587 



■ 582 

 .614 

 .614 

 .61S 



■ 633 



■ 634 

 .636 



■ 639 



■ 650 



■ 627 



■ 631 



■ 649 

 .648 



■ 6S7 



■ 653 

 .670 

 .658 

 .671 

 .672 

 .676 



■ 694 

 .699 

 .692 



Smithsonian Tables. 



