38 



NEW YORK STATE MUSEUM 



Fig. 12 Bastite rock at Hortontown. Actual size 3 mm. 

 Showing a network of bastite needles and spindles with 

 many grains of magnetite 



tiicols the latter appears as a network of spindles, flakes and needles 

 of bastite. There seems to be no trace of an antecedent mineral 

 (see figure 12). 



The ledges of the 

 black rock are prevail- 

 ingly rusty. Excavation 

 has been made at one 

 place to a depth of two 

 or three feet, apparently 

 in a search for ore. 



These ledges are in- 

 conspicuous, and, when 

 surrounded and over- 

 grown by grass, are 

 readily missed, except 

 in systematic search. 



The hand specimen 

 shows a very coarse tex- 

 ture. The rock is made 

 up chiefly of massive 

 hornblende. There are 

 patches of finer texture in which magnetite is abundant. Small 

 pyrite grains are frequent. In some places the hand specimen 

 shows a relatively porous mass of rounded grains as though some 

 mineral had been dissolved away. The rock has a high specific 

 gravity and in almost all cases is rusty in color. The thin section 

 shows large, irregular pleochroic brown and green hornblendes, with 

 some pyroxene. Magnetite inclusions are numerous and this min- 

 eral also occurs abundantly along numerous cracks, sometimes in 

 association with serpentine borders or fillings. 



The ledges of the quartzite are more numerous and more ex- 

 tensive than those of either of the other rocks. Its apparent width 

 is about 75 or 100 feet. It is thin-bedded and steeply inclined. It 

 is very similar to the basal quartzite as seen at certain places and 

 appears to belong to that formation. It may be followed distinctly 

 for several hundred feet. 



At the north and south these types give way to the characteristic 

 gneisses of the mountains. 



The exact field relations of these rocks are very obscure. No 

 contacts could be found. Seemingly the only clue to their age and 

 relationships is to be obtained from the structural features and the 

 associations. 



