The Monoclinic Pyroxenes of Neio York State. 145 



hotel. The grains are rounded, transparent, of a light green 

 color and many have a strong basal parting. No faces were 

 found on them. An analysis of this material showed : 



Per cent. Katio. Prop, parts. 



SiO^ 54.63 .9105 22 



AlA 5.26 .0513 1 



FeO 3.00 .0416 1 



CaO 22.63 .4041 10 



MgO 14.18 .3545 9 



99.66 



The above analysis gives the formula Mg9Ca^QreiAl2Si220g7, 

 which may be considered as made up of FeSigOg, CaAlgSiOg, 

 MggCagSi^^gOgg. Thc lattcr corresponds closely to the diopside 

 molecule MgCaSigOg. 



According to Beck (Ref. 2, 289),* green pyroxene crj^stals 

 occur at this locality which show the combination a(lOO), 6(010), 

 m (110), c(OOl), |9(T01), 0(221), s(ril), and w(lll). At the 

 same place there is found a yellowish green or emerald green cocco- 

 lite, which is translucent to semi-transparent. It is associated 

 with grains of jet black pyroxene. The former is probably simi- 

 lar to the greenish granular pyroxenes in calcite from this locality 

 in the collection of the New York State Museum. 



DeLong^s Mill. — Pyroxene of a dark color occurs in Hammond 

 Township near DeLong's Mill (Ref. 2, p. 295), together with 

 zircon, feldspar and apatite. The forms noted on it are a (100), 

 b (010), m (110), and u (111). A grayish white and green variety, 

 with a strong prismatic cleavage and pronounced basal parting, 

 also occurs. A very incomplete analysis of it is given by Beck. 



Diana, Lewis County. — There is an excellent section of a con- 

 tact zone exposed on Ashmore's farm, near Natural Bridge. It 

 is along the contact of the anorthosite and limestone, and is about 

 two feet wide. The mineralogical structure of it is as follows : 

 There is next to the gabbro and shading into it a layer containing 

 abundant wollastonite. Next to this and towards the limestone 

 is a second, though not sharply defined layer, containing a mix- 

 ture of feldspar, scapolite, sphenc and zircon. Thei'e then follows 

 calcite with much pyroxene, and then coarse granular calcite, 



*The Long Pond mentioned by Emmons (Geol. N. Y., 1837, p. 31) is the 

 same locality as Cascadeville. 



