172 NEW YORK STATE MUSEUM 



exposure, it gives way in places to a nearly pure quartz aggregate. 

 Quartz is particularly abundant in the central part of the southern 

 pit where it occurs in a large zone which here and there incloses 

 a crystal or mass of pink feldspar. On either side of the quartz 

 zone for some distance occurs a mixed phase of quartz and albite 

 in pegmatitic intergrowth, with occasional segregated individuals 

 or masses of the pink feldspar, which is microcline. The pink 

 feldspar occurs by itself also in considerable bodies. The white 

 albite is mainly developed as a graphic intergrowth with the quartz. 

 Between the different phases exhibited by the feldspar, quartz and 

 intergrowths of the two, it is possible to have every gradation. The 

 conditions seem to indicate more or less segregation of the constitu- 

 ents during the process of intrusion, facilitated no doubt by the 

 extreme mobility of the magma. Lack of uniformity is rather 

 characteristic of the larger pegmatitic bodies; and similar features 

 may be seen in other occurrences though they are not so well shown 

 as in these quarries. 



The feldspar from the different workings is graded according to 

 character and content of quartz. The microcline, which occurs 

 mainly in quite pure crystals and aggregates, constitutes the first 

 grade, suitable for pottery purposes. The albite that is fairly free 

 of quartz, but not entirely so, is sold as enamel material. The 

 pegmatitic intergrowth of albite and quartz, with more or less of 

 the pink variety as well, is used in glass manufacture, scouring 

 soaps, etc. The first grade has generally been sold in crude con- 

 dition, as the mill until recently was not equipped for grinding 

 pottery material. The others were ground at the quarries. Besides 

 the feldspar, there are obtained large quantities of quartz, which 

 is shipped crude to the Bridgeport Wood Finishing Co. for wood 

 filler and silica paint material. 



The more common associated minerals included mica, tour- 

 maline, and beryl ; occasional ingredients are garnet, ilmenite and 

 some of the uranium minerals. The mica is principally muscovite 

 and occurs as included crystals in the feldspar or in the finer peg- 

 matitic intergrowths along with the feldspars and quartz. The 

 crystals seldom exceed 5 or 6 inches in diameter. They are much 

 fractured and scarcely suitable for cutting of sheet mica. The 

 biotite is in larger crystals but not so plentiful as to give much 

 trouble in its removal. The tourmaline is the common black 

 variety; it is mostly associated with the quartz as well-shaped pris- 

 matic crystals and as a thin crystalline coating on the surfaces. 

 The beryl forms flat and prismatic crystals, occasionally well- 



