ORIGIN OF THE PEGMATITES OF MAINE 



299 



pegmatite minerals are those characteristic also of the normal granites ; 

 namely, quartz, orthoclase and microcline, albite or oligoclase, mus- 

 covite, biotite, and black tourmaline. Accessory constituents nearly 

 always present are garnet, magnetite, and green opaque beryl. Acces- 

 sory minerals which are present only in certain pegmatites number 











L\~i 



- \ / ^ 





5 feet 



Fig. I. — Granite grading into pegmatite and both intrusive in schists. Shore of 

 Southport Island near south entrance of Townsend Gut. 



over fifty species; the most important are lepidolite, amblygonite, 

 spodumene, blue, green, and pink tourmaline, transparent blue, 

 green, or golden beryl, colorless to amber-colored topaz, and rose 

 and amethystine quartz. A number of pegmatites have been suc- 

 cessfully worked for certain of these gem minerals. 



In possibly ninety-nine one-hundredths of the pegmatite masses 

 in the state no unusual minerals are present, the constituents being 

 the same as in the normal granites and the proportions also somewhat 



