104 



INFRA-RED EMISSION SPECTRA. 



as one might expect from a knowledge of the absorption bands at 1.6 and 

 2.2 fi to be noticed in fig. 37. The silicate band at 2.87 /< is prominent. 

 Other bands occur at 2, 3.6, 4.6, and 5.5 /<, respectively. 



Spodumene [LiAl(Si0 3 ) 2 ]. 



(From Pennington County, South Dakota. Irregular rod, 12 by 1.5 mm. Energy 



supplied, 5.7 and 9.5 watts. Curves a and b, fig. 72.) 



This mineral contains cerium, lanthanum, and other "rare earths" as 

 impurities. It can be melted in a blast flame. Considerable light was 

 emitted, due to the presence of impurities. The emission spectrum shows 

 the silicate band, sharply defined at 2.88 /, with other bands at 2, 4.1, 4.5, 

 4.9, and 6.5 //. 



4- 5 



Spodumene. 



Beryl [Be 3 Al 2 (Si0 3 ) fi ]. 

 (Rod 10 by 3 mm. Energy, 7 to 8 watts. Curve a, fig. 73.) 



The rod was an opalescent milky glass, although the original crystal 

 was a transparent green. The temperature was probably 1100 . The 

 emission spectrum is unusual in appearance, with a sharp maximum 

 superposed upon it at 2.8 fi. Other ill-defined maxima appear to be at 

 1.7, 2.4, 2.9, 3.6, 4.4, and 4.8 ;. 



