842 



NEW YORK STATE MtTSEUM 



The following table gives the composition and fusibility of the 

 different feldspar species according to Dana. 



Name 



Orthoclase 



f Anorthite . 



-2 ! Albite . . . 



Oligoclase. 



Fusibility 

 in scafe 



Si02 



Al^O 



K 



Na o 



CaO 



FeO 



"J 



o 



^ [^ Labradorite 



5.0 64. Y 18.4 16.9 



5.0 43.2 36. Y 



4.0 68. Y 19.5 



3.5 64.0 24.0 



3.0 54.0 29.0 



• . • . • ■ jU\J • X 



< •■• -Lj^*0 ••• 



2.0 9.0 3.0 



... 5.0 11.0 







Occurrence. Deposits of feldspar are fonnd in tbe soutbeastem 

 portion of the state, near the town of Bedford, abont 40 miles north 

 of ISTew York city. In this region the feldspar together with quartz 

 forms large pegmatite veins, in the augengneiss of that region. 

 The width of some of these veins is over 50' feet. The spar 

 at times forms large masses, at other times it is more or 

 less intimately associated with the quartz, necessitating some sort- 

 ing after it is quarried, and, when streaks of mica or black tourma- 

 line are encountered in the veins, they are usually thrown out. 

 The color of the feldspar varies from dark red to a creamy white, 

 though most of it is a deep cream. The largest quarry is that 

 operated by P. H. Kinkel & Son, where a large amount of quartz 

 and feldspar has been taken out during the last 10 years. The 

 feldspar in Mr Kinkel's quarry is orthoclase, as can be seen by the 

 following analysis: 



No. 1 



SiOa 64.97 



AI2O3 , 20 . 85 



FesOg tr. 



K2O (by loss) 13. Y2 



Na^O 



H2O (by loss) .46 



CaO 



MgO 



' 100.00 



Nc 



). 2 



65 



.85 



19 



.32 





.24 



14 



• • 



.10 



• • 



.56 





08 



100 



15 



