THE ADIRONDACK GRAPHITE DEPOSITS II9 



SUMMARY OF THE SOUTHERN AREA 



It is the bedded deposits of the graphitic schists of the southern 

 area that are the commercial deposits of the Adirondack s. We have 



seen that there are four distinct types of ores. 



1 The normal quartz-schist with 5 to 7 per cent of graphite 

 which is the valuable rock at the American Graphite Company, the 

 Faxon property, the Lakeside mine, Hooper Brothers' mine, the 

 Ghamplain Graphite Company, the Adirondack Mining and Milling 

 Company, the Silver Leaf Graphite Company, the Flake Graphite 

 Company, and the Graphite Products Corporation. The rock worked 

 at all these localities is very probably the same stratigraphic unit. 

 referred to as the Dixon schist. It exists as two beds or lenses at 

 the Dixon, Faxon and probably at the Flake mines, but in the other 

 properties it is represented by a single bed. In general, the forma- 

 tion varies in thickness from a maximum of 30 feet to a minimum of 

 3 feet. The upper portions of the Dixon schist are usually mica- 

 ceous, which seems to be true of the bottom layers as well. As a 

 general habit an increase in the feldspar percentage is accompanied 

 by a rise in the biotite-chlorite content, although there are a few r 

 exceptions to this rule. 



2 The second type is the feldspar-quartz schist with 6 per cent of 

 graphite and 10 per cent of micaceous minerals. This is exemplified 

 by the Bly ore. It is the writer's opinion that this schist represents 

 a distinct and different horizon from the Dixon schist. It w 7 ould 

 seem as if it did not have such a great areal extent. This is the 

 Bear Pond schist. 



3 The third type is a phase of the Dixon schist affected by a mild 

 form of contact metamorphism, which has developed pyroxenes and 

 tourmaline and redistributed the graphite resulting in an abnormally 

 high graphite content in certain layers. This is the International- 

 Rowland-Sacandaga type. 



4 The last group has only one known representative; the Rock 

 Pond .ore, which is a meta-arkose (" arkosite "), being composed 

 almost entirely of potash feldspar. Its stratigraphic position is 

 unknown. 



There is a practical basis for such a classification. Milling 

 practice rules out, for the present, the last three classes. It may be 

 that with the development of milling processes, already suggested,' 

 some of these can be successfully worked in the future. The 

 slightly contact metamorphosed beds present a very variable rock 



