The MonocUnic Pyroxenes of New York State. 159 



dark green granrtlar pyroxene is abundant, associated with horn- 

 blende, epidote, red and white feldspar, biotite and tourmaline. 

 Much of the gneiss in the vicinity of the orebod}^ is pyroxenic. 



Tilly Foster^ Putnam Go. — Although many mineral species 

 have been described from the Tilly Foster Iron Mines, pyroxene 

 has not yet been recorded from there. It is not common how- 

 ever. There is one group of small crystals in the collection of 

 "Columbia University. 



The crystals are about \ inch long, green and transparent, with 

 smooth faces. Some show a basal parting. The general com- 

 bination of planes is a (100) and &(010) narrow, 77i(110) broad, 

 c(OOl) large, m(111), and s(lll), the latter so extended as to in- 

 tersect the front prism faces (PI. XIY, Fig. 12). The crystals 

 are embedded in calcite. 



A second and unique specimen is in the collection of Mr. F. 

 L. Nason, of New Brunswick, N. J. It is a single individual 

 about I inch long and ^ inch thick, and tabular parallel to h 

 (010). There are terminal faces at one end, but the other is 

 broken off. The planes of the prismatic zone are smooth and 

 bright, while the terminal ones are slightly pitted. The combina- 

 tion of forms is a (100), & (010), m (110), /(310), o (^21) and 

 |)(101) (PI. l,Fig. 1.) A very small dome face probably e (Oil) is 

 present. The orthoprism /(310) is very narrow and is of interest 

 as it is not known to occur on any other pyroxene from this State. 

 It was determined with the reflection goniometer. 



The extinction as measured through the transparent crystal is 

 41°ll^ 



Sp. Gr. 3.6 



There have been recently added to the Columbia University 

 collection some large crystals from this locality. The largest is 

 a prismatic individual about two inches long and without termi- 

 nations. It is permeated throughout with grains of pyrrhotite. 

 Another but well-formed crystal, is about one inch long, |^ inch 

 broad and 1^ inch thick. The faces are smooth and fairly bright 

 in places. A strong basal parting is present and the crystal is 

 slightly tabular parallel to h (010.) There is also an abundant 

 deposition of fine grains of pyrrhotite along the parting planes. 

 The following combination of forms occurs on this crystal and 

 nearly all the smaller ones found attached to it. a(100),& (010) 

 broad, m(lOl), c(OOl) small, p(T01) very large, u{l\l) small, 



