^ / 



Photomicrograph of no. 432-6. Taken with plain light, magnification about 25 diameters. 



Taken for the purpose of showing a typical distribution of feldspathic and other material with 

 the quartz of this specimen. Minerals present are: a Garnet, two large rough irregular grains. 

 6 Orthoclase, slightly altered (gray 'smooth), c Biotite, three or four small flakes at one side of 

 the field (smooth dark flakes), d A crystal of zircon (rough) associated with the biotite. e A few 

 black metallic grains (dead black) . 



The rest of the field is quartz which is believed to be the youngest constituent and forms the 

 principal mass of the whole specimen. The other rather isolated grains are believed to be remnants 

 of a previously existing rock which has been invaded and replaced and largely absorbed. 



Plate 29 



Photomicrograph of no. 432-c. Taken with crossed nicols, magnification about 25 diameters. 

 This is the same field as 432-6, taken for the purpose of showing the structural relations, especially 

 the complex interlocking -of the quartz. 



