114 NEW YORK STATE MUSEUM 



hornblende-gabbros, but except for some few small inclusions in 

 the primary feldspars none of this original hornblende remains,, 

 recrystallization having been much more complete in them than 

 in the ordinary gabbro. 



In addition to the minerals already mentioned, apatite is always 

 present, often abundantly, in these rocks; titanite, pyrite and 

 pyrrhotite occur sporadically, and a little secondary quartz fre- 

 quently appears, mostly in close association with magnetite. In- 

 the granular material a certain amount of the secondary feldspar 

 is usually without striation, and may therefore be orthoclase r 

 but no certainty in regard to this has been reached. 



These gabbros as a whole belong to the type to which the name 

 of hyperite has been given by Tornebohm. 



These rocks occur numerously in the county in the form of dikes 

 cutting the anorthosites, and such show excellently in the many 

 rock cuts along the New York Central and Hudson River rail- 

 road between Saranac and Floodwood. As examples of the 

 bosses may be mentioned; 1) one by the road along the north 

 branch of the Saranac 2 miles east of Hunter's home, which is 

 fairly coarse, of the brown hornblende variety, and has a com- 

 paratively unchanged core; 2) another well shown in cuts along^ 

 the New York and Ottawa railroad between 1J and 2 miles above 

 St Regie Falls, also of the brown hornblende variety, which shows 

 beautifully the gradual passage of the hyperite into amphibolite- 

 gneiss, the extreme phases of which are studded with very large 

 garnets mostly between 1 and 4 inches in diameter; 3) another 

 along the west shore at the head of Lower Saranac lake and run- 

 ning up on Boot Bay mountain, which is quite a large mass and 

 correspondingly coarse; and 4) still another 2 miles northeast of 

 Vermontville, a curious little area inclosed by gneisses which are 

 thought to belong to the augite syenites, in which hoth hyperite 

 and anorthosite gabbro occur with, as yet, unascertained rela- 

 tions to each other and to the inclosing rocks. 



Granite. There seem to be granites of two, possibly of three, 

 different ages in Franklin county. In considerable part they 

 have not been differentiated from one another. 



