156 The Monoclinic Pyroxenes of New York State. 



e(Oll), (7(001),p(r01). -One crystal found was 6 in. long and 10 

 in. in circumfei'ence. 



There are a number of specimens in the collection of the New 

 York State Museum which have the usual habit of Orange County 

 crystals, with the faces a(lOO), 6(010), m(llO), c(OOl), and 

 e(Oll). 



The specimens in the Columbia University collection are short, 

 stout greenish black crystals, of the combination a (100), &(010), 

 m(llO), c(OOl), and s(lll). One fresh piece was found which in 

 section gave an extinction of 42° 40'. This is very close to that 

 recorded by Doelter (E,ef. 14). The color in section was light 

 green. 



Doelter has described some augites from Greenwood Furnace 

 (Ref. 14), in which the extinction on h (010) was 42° 20' and on 

 m(llO) 31° 50'. The cr3'stals were prismatic individuals with 

 their faces somewhat roughened by alteration, but the light green 

 interior portion of them was perfectly fresh. The composition of 

 this latter portion was : 



SiOj 49.18 



FeO 2.55 



CaO 20.62 



MgO 16.83 



FeA 5-05 



AlA 5.09 



99.52 

 Sp. Gr. 3.295. 



The above calculated gives a formula Si47Ca2iMg24Al3Fe2 

 FejOjgg, which Doelter considers as consisting of the following 



silicates : 



19 (MgO, CaO, 2Si02) 

 2(CaO, FeO;2Si02) 

 2 (FeA, MgO, SiO,) 

 3(A1A, MgO, SiOa) 



He then points out that Ca : Mg : Fe : : .368 : .420 : .035 or as 

 11.5:12:1, hence Ca<Mg+Fe, as he claims is the case with 

 augites. 



Highland Township^ Orange Go. — Granular pyroxene is not 

 uncommon around many of the small ore bodies found in the 

 township. 



There is one specimen of granular augite in the Columbia 



