9& NEW YORK STATE MUSEUM 



dealers. The rock is an interesting type, as it belongs to the true 

 granites, being composed of feldspar and quartz in normal pro- 

 portions, but on the other hand contains no dark silicates of the 

 mica, amphibole or pyroxene families. In the place of such min- 

 erals, however, it carries a large amount of magnetite which ordin- 

 arily is a very minor constituent of granite. This mineral con- 

 stitutes about 15 per cent of the entire rock, its relative abundance 

 more than compensating for the absence of iron-magnesia silicates 

 in effect upon the specific gravity. The latter is 2.8 which cor- 

 responds to a weight of 175 pounds to the cubic foot, which is very 

 high for granite. The color is purplish brown to dark red. The 

 grain is regular and fine, the average diameter of the quartz and 

 feldspar grains being under 2 mm. The appearance of the polished 

 surfaces is attractive. 



The quarry is a small opening with a face of about 12 feet. It 

 is on property owned by Mrs Beane of Ausable Forks. 



THE KEESEVILLE ANORTHOSITE AREA 



The anorthosite exposures in the vicinity of Keeseville near Lake 

 Champlain, have been the source of fairly large quantities of build- 

 ing and monumental material. The rock is mostly the light, granu- 

 lated variety that characterizes the peripheral zone of the great 

 Adirondack mass. The stone has been sold under the name of 

 Ausable granite. 



Prospect Hill quarries 



The Prospect Hill quarries are situated on the northern and 

 western slopes of that prominence, a rounded knob 300 feet or more 

 high, lying just south of Keeseville. The northerly quarries once 

 belonged to the Ausable Granite Co., and are mentioned by Smock 

 as in active operation at the time of his investigation in the period 

 1880-90. The company also operated a dressing and monumental 

 works at Keeseville. 



The stone of these quarries is medium to coarse in texture, de- 

 pending on the relative proportion of the granulated and residual 

 uncrushed feldspar, and has a gray color. The rock surfaces show 

 glacial striations and polishing, but are almost unaffected by weather- 

 ing influences. 



Smock describes two quarries as operative, a lower one to the 

 north producing a coarse variety, and an upper quarry about 20 

 rods south of the former and higher up the hill, each equipped with 

 a single derrick. The quarrying of dimension stone must have been 



