58 INFRA-RED TRANSMISSION SPECTRA. 



APATITE (Ca 5 F(PO4) 8 ). 



(From Kragerve, Norway. Massive; subtranslucent ; f = o.i2 mm. 



Curve b, fig. 44.) 



There are no strong bands in this mineral, and none are found to be 

 common with substances containing the PO 4 radical. The bands are 

 small and occur at 2.9, 3.9, 4.85, 5.85, 6.4, and 6.85 /tt. 



01234-56 



FIG. 44. Potassium chlorate (a) ; Apatite. 



GARNET (Ca(Fe,Mg) li Al a (SiO)8). 

 (f = 3.25 mm. Curve a, fig. 45.) 



This garnet was wine-red in color, showing absorption bands in the 

 yellow-green and in the green-blue parts of the spectrum. 



The transmission curve is extraordinary, having a wide absorption 

 band extending from 1.2 to 2.6 //,, and complete opacity beyond 4.5 ju,. 



MONAZITE, (Ce,La,Di)PO4. 

 (t = 1.04 mm. Curve b, fig. 45.) 



This brown-colored mineral was partly transparent to visible rays, 

 and is equally opaque to infra-red rays. A large band extends from 

 3.5 to 5.5 p., and opacity beyond 6.5 //,. 



