524 



NEW YORK STATE MUSEUM 



From which the norm is : 

 Or. Ab. An. 



33 08 35.. 3 2 9.79 



Sal. 94.55 



Mt. 

 1.84 



Di. 

 2.03 



Hy. 



1 . 40 



Qz. 

 16.36 



Total 

 99.82 



Class, 



Orde 



Ran.?, 



Fern. 5.27 

 Q = i6. 3 6 = 

 F 78.19 

 K 2 0' + Na 2 0' 



1, persalane 



21 = 4, britannare 

 127 



Subrang, 



CaO' 

 K 2 0' 

 Na 2 0' 



44 



2.9 = 2, toscanase 



= — = . 88 = 3, toscanose 



A coarse, red, porphyritic syenite which is very quartzose, com- 

 poses the steep cliffs on the south end of the big ridge known locally 

 as Follensby mountain, which lies southwest of Follensby pond. Its 

 mineralogy is the same as the previous rocks except for holding 

 augite in addition to hornblende. In the calculation the augite 

 was assumed to have the composition of the diopside from the 

 laurvikite near Laurvik, Norway. 1 While that is more basic it is 

 otherwise a similar rock to this, and the augite has the same char- 

 acter as that in the more basic syenites which closely correspond to 

 Brogger's rock. For the sake of brevity the details of the calcula- 

 tion are omitted. 



Mode, composition and norm of toscanose (10-D-3) 



Units measured 



% weight 



Composition 



Norm 



Microperthite 



Quartz 



Plagioclase. . . 

 Hornblende . . 



Augite 



Magnetite. . . . 

 Apatite 



1760 



898 



72 



q6 



67 



1 

 1 



59-5o 

 3°-93 



Total 2895! 100.00 



Si0 2 74-17 



AI2O3 13 .30 



Fe 2 3 0.26 



FeO 0.77 



MgO 0.81 



CaO 2 .34 



Na 2 3.43 



K 2 4.53 



P2O5.. . . . . 0.02 



99-63 



Or 26.80 



Ab 28.98 



An 7.48 



Di 3-27 



Hv 1.68 



Mt 0.37 



Qz 31-64 



Class, = — — = 



95-9o 



Fern. 



= 19 



1, persalane 



Order, 



5.22 

 Q 31.64 

 F = 63~l6 = • 5 = 4, britannare 



„ K 2 0' + Na 2 0' 103 



Rang, t^tFv = ~u =2.4 = 2, toscanase 



Subrang, 



CaO' 

 K 2 0' 

 Na 2 0' 



48 

 55 



42 



87 = 3' toscanose 



1 Brogger, Eruptivgest. Kristianageb. 3:23. 



