BASIC (aMPHIBOLITE) GNEISS 389 



as seen in figure 12. Counts of the areas occupied by these minerals in 

 several thin sections are given in tables 7 and 8. 



Tai!le 7. — Mineral Compositions of typical basic Gneisses 



1 



Quartz 13. 8 



Feldspars : 



Oligoclase 48. 5 



Audesiiie 2.5 



Orthoclas- 1.0 



Hornblende 24.6 



Augite 8.0 



Accessories 



Ilmenite 1 . 55 



Zircon 0.05 



2 



3 



4 



17.8 



27.8 



25 



49.0 



52.9 



45 



.... 



2.8 



3 



1.3 



0.6 



1 



27.8 



3.8 



20 



4.0 



11.0 



5 

 1 



0.05 



1.05 





0.05 



0.05 



... 



Totals 100.00 100.00 100.00 100 



The localities represented are as follows, all being on the Allentown quad- 

 rangle : 



1. One mile northeast of Limeport (7916). 



2. West end of Seidersville (5873). 



3. One mile southeast of Mountain ville (290). 



4. The rounded-off average of 1, 2, and 3. 



Table 8. — Mineral Compositions of unusual basic Gneisses 



12 3 



Quartz 5.0 2.0 



Feldspars : 



Orthoclase 2.6 5.2 



Microperthite 51 . 4 



Oligoclase 1.2 54.0 



Andesine 65 . 2 



Hornblende 14. 8 



Augite 39.5 



Hypersthene 25.6 17.8 



Biotite 14. 8 



Accessories : 



Ilmenite 0.1 0.4 0.2 



Titanite 0.2 



Totals 100.0 100.0 100.0 



These are from : 



1. One mile southeastof South Bethlehem (5869). 



2. Near Seidersville (335). 



3. One mile east of Freemansburg (6458). 



