524 



NEW YORJ<: STATE MUSEUM 



From which the norm is : 



Or. Ab. An. Mt. 



33-oS 35.32 9.79 1-84 

 Sal. 94-55 ^ ^^ 



Di. 



2.03 



Hy. 

 I .40 



Qz. 

 16.36 



Total 

 99 . 82 



Class, -^ 



Order, | 



Fern. 5.27 

 16.36 _ 



Rang, 



78.19 

 K2O' + NasO' 



Subrang, 



CaO' 



Na20' ^ 



== I, persalane 

 = 4, britannare 



2, toscanase 



127 

 44 



59 

 67 



= 2.9 



= 3,- toscanose 



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

 poses the steep diffs 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.^ 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 



Microperthite ... 1760 



Quartz 898 



Plagioclase 72 



Hornblende 96 



Augite.- 67 



Magnetite i 



Apatite i 



% weight 



Total 2895 100.00 



59-5° 

 30-93 

 2.47 

 4 . 12 

 2.87 

 0.07 

 0.04 



Composition 



Norm 



Si02 74-17 



AI2O3 13-30 



Fe203 0.26 



FeO 0.77 



MgO 0.81 



CaO 2.34 



Na20 3 43 



K2O 4-53 



PzO, 0.02 



Or 26.80 



Ab 



An 



Di 



Hv 



Mt 



Qz 



99-63 



28 



98 



7 



48 



3 



27 



I 



68 







37 



31 



.04 



100 



.22 



Class. S^ _91^ = 19 = I, persalane 

 Fern. 5.22 



Order, 2 = |^ =.5 = 4, britannare 



K201jLN^20;,_Z^_ 2.4 = 2, toscanase 

 ^^^^' ^CaO' 42 



9iibranp =i-= .87 =3, toscanose 



bubrang, ^^^q, ^^ / ^' 



; \ 



I Brbgger, Eruptivgest. Kristianageb. 3:23. 



