140 A. F. Bl'DDINGTON 



a homogeneous felt of exceeding minute microscopic scales and 

 fibers of pyrophyllite, with a strong tendency toward a very good 

 alignment parallel to the cleavage in a section at right angles to 

 it and with long, parallel, fibrous shreds in a section approximately 

 parallel to the cleavage. 



No. 6 (222 E 2 g). A white quartzose nodule or lense of quartz- 

 pyrophyllite schist about 1 foot in diameter taken from a pyro- 

 phyllite vein at talc prospect 1. In thin section the rock presents 

 what might be called a micro-blotchy groundmass composed of 

 aggregates of either microcrystalline quartz or of scales of pyro- 

 phyllite. Some fibers of pyrophyllite also occur interstitially in 

 the quartz areas. 



No. 7 (228 D 1 //). This is the dark grayish-olive, waxy- 

 lustered matrix of the spherulitic rhyolite illustrated in Fig. 4. In 

 thin section the rock is seen to consist of an aggregate of extremely 

 fine shreds and scales of white mica with lines of partially replaced 

 microcrystalline quartz which are probably replacements of certain 

 of the original rhyolite flow lines not yet entirely replaced by the 

 white mica. 



No. 8 (232 E 2 b). Grayish-olive pinite schist with small 

 unaltered spherulites or spherulites partially replaced by quartz. 

 In thin section the material appears as a perlitic microcrystalline 

 groundmass of quartz and orthoclase partially replaced by sericite. 

 The perlitic cracks are outlined by threads of sericite fibers, as 

 illustrated in Fig. 6, and they often form the boundaries of sero- 

 citized areas which present the appearance of eyes, sometimes with 

 a reticulating network of sericite veins connecting two adjacent 

 eyes. Within the sericitic material, isolated microspherulites, 

 clusters of microspherulites, and long axiolites are often preserved 

 intact. A few phenocrysts of orthoclase are present and are 

 remarkably fresh, although occasionally flecked with sericite. The 

 secondary material consists of an aggregate of microscopic sericite 

 scales and fibers associated with grains and areas of secondary 

 quartz. Minerals originating through decomposition at the sur- 

 face are completely absent except for a trace of iron oxides in the 

 groundmass and a slight cloudiness in the feldspars, probably due 

 to kaolin. 



