150 The Monoclinic Pyroxenes of New York State. 



Natural Bridge, but none of them showed any good terminal 

 faces. The faces of the prismatic zone were usually easily recog- 

 nizable and smooth. The crystals are dark green to black. Only 

 three specimens have been found in the collections examined, 

 which were labeled as having come from this locality. One is a 

 group of grayish black crystals in the collection of Hamilton 

 College, showing the forms a (100), 6(010) narrow, m(llO) large, 

 It (111), 0(221) and s (111) small. (PI. XY, Tig. 9.) The pyra- 

 mid faces are etched with longitudinal interrupted striations, 

 those on u (111) being parallel to a (100), while those on o (221) 

 are parallel to h (010). The other two specimens above mentioned 

 are single crystals in the collection of Columbia University, 

 School of Mines. They are black with a greenish coating, and 

 doubly terminated. The combination of forms noted on both is 

 a (100) and &(010) very narrow, m(llO) large, m (111), s (111), 

 o(221) and z (021) very small. These crystals are very like the 

 form usually labeled as having come from Diana. 



Oxbow, Jefferson Co. — Pyroxene occurs on the shore of Yroo- 

 man's Lake (Ref. 2, p. 290), near Oxbow. It is of a green color 

 and associated with crystallized mica. The forms recorded are 

 a (100), & (010) narrow, m(llO) broad, c (001), and §(111). The 

 only specimen which the writer has seen from this locality is in 

 the Root Collection at Hamilton College. The crystals are simi- 

 lar to those described by Beck and show the planes a (100), 

 & (010), m (1 10), M (111), s (111), and o (221). 



Pitcairn, St. Lawrence Go. — The green augites from this lo- 

 cality have bright prismatic faces and striated terminal ones. 

 The crystals occur singly or in clusters and are invariably inter- 

 grown with microcline and albite.* A prismatic cleavage and 

 basal parting are generally present, though the former is only 

 seen in thin sections. The crystals are mostly two to three 

 inches long and about an inch thick. Doubly terminated indi- 

 viduals are not rare, and a common habit is a flattening parallel 

 to h (010). The terminal faces are always covered with inter- 

 rupied striae. The most general combination of forms is a (100), 

 6(010), m (110), u (111), s(Tll), and o (221) (PL XIII, Fig. t). The 

 basal pinacoid c (001) is not uncommon, and p (101) was noticed 

 on one specimen in the Columbia University collectiom Another 



*L. M. Luquer, School of Mines Quarterly, XIV, p. 328. 



