158 The Monoclinic Pyroxenes of New York State. 



county. The crj'stals of this group vary in length from a frac- 

 tion of an inch to several inches. The base is often very narrow. 

 Still another specimen from Monroe township in the same collec- 

 tion shows the combination a (100), 6(010), m (110), t^(lll). 

 s( 111), 0(^221) and ^ (021), the latter very small, (PI. XIII., 

 Fig. 5). 



There is in the Columbia TJniversit}^ collection a single cr^^stal 

 from Monroe township. It is black with rough faces and about 

 an inch long. It is tabular parallel to a (100) and shows the 

 forms a (100), 6(010), m (110) and e(Oll), (PI. XY, Fig. 1). 

 Growing out of one end is a smaller crystal of the same form and 

 habit, the axes of the two being parallel. The larger individual 

 is twinned parallel to a (100), but the smaller one is not. 



Montrose, Westchester Go. — A gray or red augite associated 

 with plagioclase occurs in the gabbros of the Cortlandt Series 

 south of Peekskill. (Ref. 57 and 59). Both colors often appear 

 in the same individual. The mineral shows no pleochroism, but 

 frequently has a strong orthopinacoidal parting, and the meta- 

 morphism which the rock has undergone has often produced a 

 peripheral granulation of the augite. The diorites of this region 

 show excellent examples of the passage of pja'oxene to compact 

 brown hornblende. 



The limestone around the Cortland area often contain a gran- 

 ular lime bearing pyroxene along and the near contact, and green 

 pyroxene is similarly developed in the limestones at Stony Point 

 on the West Shore Railroad. It is here associated with light 

 green hornblende, zoisite, titanite, and much scapolite. 



Bosetown, Rockland Go. — Grreen augite is a common constituent 

 of the diorites near this locality (Ref. 22). It is closelj^ asso- 

 ciated with less basic hornblende which was formed before it. 

 An analysis of this augite made 'bj Prof. Kemp gave : 



Percentage. Ratio. Prop, parts. 



SiO^.... 46.00 .76 10 



AlA 14.80 .134 2 



FeA 11.20 .07 1 



MgO 4.75 .119 2 



CaO 15.52 .277 4 



Na^O 3.20 



K2O 4.70 



100.17 

 Tuxedo Township, Orange Go. — At the Sterling Iron Mines 



