The Monoclinic Pyroxenes of New York State. 161 



presence of fluorite, chondrodite and warwickite indicate mineral- 

 izers. 



The pyroxene crA^stals occurring in the scapolite zone are darli 

 green, and in section light green. The faces of the prismatic 

 zone are a (100), 6(010) and m (110), equally developed; they are 

 smooth, but dull. As a rule terminal faces are rare, but when 

 present the usua^l combination of forms is u (111), o (221), s (111), 

 c(OOl) and p(lOl). The greater development of p(TO]) over 

 c (001) is a characteristic feature of these crystals. A basal part- 

 ing due to twinning is often apparent, especially in sections, and 

 a prismatic cleavage is not rare, but likewise is often only to be 

 seen in sections. 



PL II, Fig. 7, shows the prismatic form and PI. II, Fig. 6, the 

 terminated form of these pyroxenes. 



The composition of this dark green augite is : 



Percentage. Eatio. Prop, parts. 



SiOa 52.01 .866 206 



FeO 6.86 .094 22 



CaO 26.90 .480 100 



MgO 11.26 .281 70 



Fe^Oa 67 .0042 1 



AlA 5.82 .0568 14 



Alkalies 50 



99.92 

 Sp. Gr. 3.6. 



The formula obtained from the analj^sis is Ca^o^, Mg^^, Fe22, 



l!e2, Algg? ^512067 ^6495 O^" 



22 (CaFeSlA)- 



MgFe^SiOe: 



11 (CaAl^SiOe). 



3 (Mg Alo SiOe). 



66 (CaMgSiA)- 



c:c = 45°15^ 



Beck (Ref. 2) mentions the occurrence, one mile northwest of 

 Edenville, of dark green or black crystals of pyroxene associated 

 with apatite, hornblende, titanite and calcite. A form is also 

 said to occur at Warwick Mountain, which has the forms a (100), 

 h (010), m (110), c (001) and e (Oil). 



This same township, Warwick, has furnished the well-known 

 tabular crystals of Leucaugite which have attracted so much 



