The Monoclinic Pyroxenes of New York State. 163 



Much of the serpentine found at Amity may result from the 

 alternation of pyroxene. (Ref. 33). 



Several analyses of pyroxenes from Edenville have been pub- 

 lished, but little information is given concerning the material 

 from which they are made, or the exact locality. One of these is an 

 analysis of pyroxene from Edenville, by Brewer, as follows. 

 (Ref. 4): 



Percentage. • Ratio. Prop, parts. 



SiO^ 36.94 .615 19 



FeO 36.03 .109 14 



CaO 12.71 .227 17 



MnO 2.24 .0312 1 



AI2O3 .11.22 .109 4 



99.14 

 This analysis gives 



Ca^Fe^MnAlgSiigOg which we may consider as a mixture of 

 4(CaFeSio06) 



SCCaAlaSiOg) 



AloSigOg 



leaving MnSi^On or approximately Mn2Si20e+3Si02 



Leucaugite. 

 Amity ^1 Orange Go. Leucaugite of light brown color occurs in 

 grains or rounded crystals, associated with c^lcite and seybertite, 

 and is identical with leucaugite from Bathurst, W. Canada,. 

 (Re^ 31.) 



Percentage. Ratio. Prop, parts. 



SiOa 50.05 .834 238 



CaO 25.63 .458 131 



Mgo 14.48 .362 103 



FeaOs 56 .0035 1 



AI3O2 7.16 .07 20 



HaO.^ 1.66 



99.54 

 Sp. Gr. 3.26 

 Prom this analysis we obtain the formula 



CaisiMgiosFezAl^oSiosgOyja which is made up of 

 MgFejSiOg 

 20(CaAl2SiO6) 

 Mgio2 Cam Siaie ^m 

 the latter being approximately Mg Ca SijOg 



The dolomitic limestones of Westchester, Dutchess and New 

 York Counties often contain crystals of white pyroxene in great 



