Fig. I Photomicrograph of Poughquag quartzite, Peekskill area ; taken 

 in ordinary light, magnification 65 diameters. This shows the distribution 

 and quantity of minerals other than quartz; the larger triangular-shaped 

 dark mineral is an almost-basal section of tourmaline ; leucoxenized ilmenite 

 and rutile make up the rest of the dark spots. 



