284 



Table 341. 

 INDEX OF REFRACTION. 

 Selected Uniaxial Minerals. 



The values are arranged in the ordef of increasing indices for the ordinary ray and are for the sodium D line unless 

 otherwise indicated. Selected by Dr. Edgar T. Wherry from a private compilation of Dr. Ksper S. Laisen of the U. S. 



Geological Survey. 



Mineral. 



Formula- 



Index of refraction. 



Ordinary 

 ray. 



Extraordinary 



ray. 



(a) Uniaxiai, Positive Minebals. 



Ice 



Sellaite 



Chrysocolla . . . 



Laubanite 



Chabazite 



Douglasite .... 

 Hydronephelite 

 Apophyllite . . . 



Quartz 



Coquimbite. . . 



Brucite 



Alunite 



Peiinmile 



Cacoxenite. . . . 



Eudialite 



Dioptasite .... 



Phenacite 



Parisite 



Willemite 



V esuvianite ... 

 Xenotime .... 



Connellite 



Benitoite 



Ganomalite . . . 



Scheelite 



Zircon 



Powellite 



Calomel 



Cassiterite .... 



Zincite 



Phosgenite. . . . 

 Penfieldite .... 



lodyrite 



Tapiolite 



Wurtzite 



Derbylite 



Greenockite. . . 



Rutile, 



Moissanite. . . . 

 Cinnabarite . . . 



HzG 



MgFz 



CuO.SiO2.2H2O 



2CaO.Al2O3.5SiO2.6H2O 



(Ca, Na2)O.Al203.4Si02.6Hi!0 



2KCl.FeCl2.2H2O 



2Na2O.3Al2O3.6SiO2.7H2O 



K20.8Ca0.i6Si02.i6H20 



Si02 



Fe2O3.3SO3.9H2O 

 MgO.H20 



K/O.3AI2O3.4SO3.6H2O 

 S(Mg, Fe)O.A!203.3Si02.4H20 



2Fe203.P205.I2H20 



6Na20.6(Ca, Fe)0.2o(Si, ZrjOj.NaCl 



CuO.SiO2.H2O 



2BeO.Si02 



2CeOF.CaO.3CO2 



2ZnO.Si02 



2(Ca, Mn, Fe)0.(Al, Fe)(OH, F)0.2Si02 



Y2O3.P2O5 



20CUO.SO3.2CUCI2.20H2O 



BaO.Ti02.3Si02 



6Pb0.4(Cu, Mn)O.6Si02.H2O 



CaO.WOs 



Zr02.Si02 



CaO.MoOa 



HgCl 



SnOa 



ZnO 



PbO.PbCh.CO* 



Pb0.2PbCl2 



Agl 



FeO.fTa, Cb)20s 



ZnS 



6FeO.Sb203.5TiO» 



CdS 



Ti02 



CSi 



HgS 



{b) Uniaxiai. Negative Minerals. 



Chiolite 



Hanksite . . . 

 Thaumasite . 

 Hydrotalcite 

 Cancrinite. . 

 Milarite . . . . 

 Kaliophilite . 



Mellite 



Marialite . . . 

 Nephelite . . . 



2NaF.AlF3 



11Na2O.9SO3.2CO2.KCI 



3CaO.C02.Si02.S03-i5H20 



6MgO.Al203.C02.isH20 



4Na2O.CaO.4Al2O3.2CO2.9SiO2.3H2O 



K2O.4CaO.2Al2O3.24SiO2.H2O 



K20.Al203-2Si02 



AI2O3.C12O9.18H2O 



"Ma" = 3Na2O.3Al203.i8Si02.2NaCl 



Na20.Al203.2Si02 



342 

 461 



46S 

 498 



496 

 529 



533 

 511 

 537 

 538 



Smithsonian Tables. 



