GEOLOGY OF THE LUZERNE QUADRANGLE 63 



The only granite visible is the usual biotitic, medium-grained, pink- 

 ish gray rock so common throughout the quadrangle. Here, as well 

 as elsewhere in the quadrangle, the Grenville has been more or less 

 injected by the usual granite and not by the imaginary "Algoman " 

 granite. 



Feldspar 



Several attempts have been made to mine feldspar within the 

 quadrangle. The most important mine is situated between ij4 and 

 i^ miles southwest of Linwood school. The northern opening, 

 about 100 feet long, is in a pink, coarse-grained, pegmatite dike 

 fully 25 feet wide with north-south strike. One-eighth of a mile 

 farther south there is another long shallow opening presumably in 

 the same dike. This part of the mine was worked as late as the 

 spring of 1920. The crudely formed crystals of pink potash feld- 

 spar commonly range in size from 2 to 10 inches. An interesting 

 feature of this pegmatite dike is that it is more or less crudely 

 foliated. Where the pegmatite djke (or tongues of it) cut the 

 adjacent amphibolite or metagabbro considerable magnetite in 

 masses up to 5 or 6 inches across occur in it, the magnetite appar- 

 ently having been absorbed from the old gabbro by the pegmatitic 

 fluids during the intrusion. 



On the northeastern slope of Mount Anthony at an altitude of 

 about 1000 feet, i mile south of Luzerne, a large pegmatite dike 

 cutting metagabbro has been considerably opened up apparently in 

 an attempt to mine the white feldspar which occurs in masses up 

 to several inches across. 



Near the top of the steep mountain (altitude, nearly 2000 feet) 

 i}4 miles north of West (Hadley) mountain, a small attempt has 

 been made to open a feldspar mine in a pegmatite dike cutting 

 granite. 



Building Stone 



Excellent building stone, especially the facies of the syenite and 

 granite, abound within the quadrangle, but very few quarries have 

 been opened in these rocks. The largest quarry is in the granite 

 just west of the road 2 miles northeast of Hadley hill (see map). 

 The rock is mostly gray to pink, medium-grained, well-foliated 

 granite locally varying to grano-syenite. Many very narrow bands 

 of pegmatite lie in the granite parallel to its foliation, and some 

 pegmatites cut across the foliation. Much cut stone has been 

 obtained here, probably mostly for railroad construction. 



