A SPECIMEN OF ITACOLUMITE. 



321 



The microscope, however, does not confirm this view, but 

 indicates that the hard quartzite has been transformed to 

 itacolumite, as a result of weathering, certainly, but by solu- 

 tion of the surfaces of the quartz grains, which happen to be 

 of rather peculiar form. 



iM(.. ti. 



Fig. IIT. 



On reference to Fig. II. (a photo of a section of the un- 

 altered quartzite, magnified 45 diameters, taken with polarised 

 light) it will be seen that no cementing material is apparent, 

 but the curiously-interlocked and dovetailed form of the quartz 

 grains is very noticeable. 



