86 



INFRA-RED REFLECTION SPECTRA. 



AMPHIBOLE (CaMg 3 (SiO))- 



(Curve a, fig. 73.) 



The general trend of the reflection curve is similar to quartz. There 

 are maxima at 8.7, 9.45, 10.03, an d 1 1 P-> tne fi rst an d last being small 

 and not well defined. 



5O/o 



56 769/0 



FIG. 73. Amphibole (a) ; Sodium biborate. 



SODIUM BIBORATE 



(Curve b, fig. 73.) 



This substance is a glass made by fusing borax. The surface was 

 well polished ; nevertheless the reflection bands are weak. The maxima 

 are wide and occur at 7.5 and 10 /*. From a comparison with the trans- 

 mission curve it appears that the great opacity of this glass is due to 

 some other property than to bands of selective reflection. 



7 B 9 IO 



FIG. 74. Datolite(a); Hydrotalcite. 



/3/J. 



