SILICATES. 



8 9 



Pfund 1 has published a reflection curve of glass, which is entirely 

 lacking in these small bands, due to the fact that only six spectrometer 

 settings were made between 8 and I2/*, while nineteen settings were 

 made in the present work. 



GRANITE. 

 (From Barre, Vermont. Fig. 77.) 



Granite is a mixture of quartz, feldspar, and mica, and hence gives a 

 reflection spectrum which is the composite of these minerals. In the 

 present specimen the mica plates were partly broken off the surface in 

 polishing. 



25% 



O 

 U 



<*- 



<D 



6 69 



FIG. 77. Granite (a); Porcelain. 





PORCELAIN (GLAZED). 

 (Curve b, fig. 77.) 



The specimen was a flat fragment of a glazed white porcelain dish. 

 As is well known, porcelain ware is made from kaolin, which is the 

 decomposition product of aluminous minerals, especially the feldspar of 

 granitic rocks. 



The reflection curve shows maxima at 8.5 and 9.25 p.. 



PECTOLITE (HNaCa 2 (SiO 8 ) 8 ). 

 (Curve b, fig. 78.) 



The specimen examined was spindle-shaped, consisting of two masses 

 of needle-shaped crystals grown end to end. The reflecting surface 



1 Pfund : Astrophys. Jour., 24, p. 25, 1906. 



