The Monoclinic Pyroxenes of New York State. 153 



Percentage. Ratio. Prop, parts. 



MgO 5.73 .0932 2 



AI2O3 6.66 .065 1 



H2O 33 



MnO ._^ t^ 



101.01 



This gives Ca7Mg2re3Al2Sii4043 or approimately 



3 (CaFeSijOe) 

 2 (CaMgSioOg) 



CaAljSiOe 



CaSiOa 



A brown and black granular pyroxene is associated with the 

 crystallized material and the composition of this as analyzed by 

 the same author was found to be 



Percentage. Ratio. Prop, parts. 



SiO^ 51.00 .85 22 



FeO 14.43 .20 7 



CaO 23.00 .4107 10 



MgO 6.26 .1545 5 



AlA 3.00 .0293 1 



h/o 66 



MnO tr 



98.35 

 This gives CaioMg5re7AloSi22069 or approximately 



7(CaFeSi206) 



3(MgCaSiA) 

 MgAlaSiOg 

 MgSiOj 



Bossie, St. Lawrence Go. — Most of the individuals from this lo- 

 cality are large green crystals, with smooth dull faces and glassy 

 interior. Those specimens in the collections of Columbia Univer- 

 sity have evidently come from a vein in the anorthosite at its con- 

 tact with the limestone. Most of the crystals exhibit the com- 

 mon basal parting, and the combination of faces observed on all is 

 a (100), 6(010), m (110), u (111), o ( 221), and s (111); c (001), also 

 occurs on some. One figured by Prof. Penfield in Dana's System 

 of Mineralogy shows a (100), 6(010), m (110), u (111) and o(221). 

 (PL XYL, Fig. 5). 



Prof G. H. Williams has described a crystal of pja'oxene col- 

 lected at Grassy Lake near Rossie, CRef. 58), and which is now 



