i6o 



NEW YORK STATE ^fUSEUM 



by Dr Henirich Ries in his valuable paper on the " Pyroxenes of 

 New York State," Annals of the Xew York Academy of Sciences, 

 volume 9, page 171 and figures 9 and 10 on plate 14. They 

 have yielded eight or ten of the faces found on the more com- 

 1: Heated pyroxene crystals. Dr Ries analyzed the crystals with the 

 results given under column i below. The specific gravity is ^.2^. 



:\Iuch careful study has been given by Dr George P. ^^lerrill to 

 the diopside masses from which the serpentine of the ophicalcites 

 has been derived. An unaltered nucleus was separated by him 

 and analyzed with the results in column 2. The serpentine is 

 given in column 3. The two analyses of the diopside are strik- 

 ingly alike. 

 ^ \ I i 3 



SiO^ 54-57 55-26 42.17 



CaO 23.25 24.48 



^IgO 17.78 19.53 



PeO 1.80 .57 



MnO tr 



K.O .70 



AI2O3 I. 12 -22 



Fe.O. ^ .22 



Ign •* .38 



H2O 



Total 99 . 60 ICO . 2% 



41 



•64 





I 



•30 



•57 



13 



7-' 



99 



• 12> 



Each of these is almost pure diopside (Ca]\lg)0. SiOo. The 

 serpentine evidently results from the disappearance of the lime 

 and seme of the silica, and the assumption of water. 



In association with the iron ores and especially in the pegmatitic 

 streaks involved in them crystals of black augite occasionally ap- 

 pear. One of these gathered by the writer at the Cheever mine 

 has been figured by Dr Ries in figure 8. plate 14 of his work 

 just cited. An analysis yielded 



Si02 FeO CaO ^IgO AI2O3 Fe.Os T6tal 



49.12 * 15.98 17.30 6.06 7.49 3.53 99. -:8 



Specific gravity 3.60 



T^rom the presence of the sesqui-bases this is obviously an augite. 



In the ore of the Old Bed group at ^lineville a pyroxene of an 

 emerald-green color is frequent, and is similar to the one in the 

 neighboring syenitic rocks. Its color strongly suggests that it is 

 related to aegirite and that it contains the soda-iron molecule in 

 large amount. 



Pyrrhotite is rare in the larger mines although seen in some of 

 the smaller sulfurous ones. It is not uncommon in the bunches 



