ORIGIN OF THE PEGMATITES OF MAINE 311 



finer-grained pegmatite bodies of tiie state. Tests of the quartz from 

 graphic granite in the quarry at Topsham, Maine, and a similar 

 graphic granite collected by the writer from Portland, Conn., 

 also showed high-temperature characteristics. Similar results were 

 obtained with graphic granite from the Urals in Russia. 



In contrast to the high temperature of formation indicated by 

 these quartzes, tests upon specimens of rose quartz from the Maine 

 pegmatites and from typical granite pegmatite at Bedford, N.Y.,' 

 indicated crystallization at temperatures below 575°. Similar low- 

 temperature characteristics were also exhibited by a sample from a 

 large mass of white quartz from Topsham, Maine. This graded 

 into quartz of graphic granite which when tested showed high-tem- 

 perature characters. Quartz from a cluster of well-defined crystals 

 occurring in a miarolitic cavity in pegmatite in Topsham showed 

 low-temperature characteristics. This quartz group interlocked at 

 its base with the feldspar of the wall of the pocket and plainly crystal- 

 lized with the rest of the pegmatite mass. Quartz associated with 

 lepidolite and albite in the gem-bearing portion of pegmatite from 

 Poland, Maine, showed low-temperature characteristics. A pyra- 

 mid-tipped prism of quartz from Topsham, projecting into a feldspar 

 crystal in the midst of coarse pegmatite and plainly a contemporaneous 

 crystallization, showed low-temperature characteristics. Crystals 

 of smoky quartz from Poland, developed on the walls of pockets, 

 showed low-temperature characteristics. 



The results of these tests are consistent among themselves and 

 in accord with the order of crystallization of various portions of the 

 pegmatite established by field evidence. While it is unsafe to draw 

 sweeping conclusions from a rather small number of tests, these are 

 nevertheless highly suggestive, and render it very probable that while 

 many of the finer-grained pegmatite masses crystallized above 575° C, 

 certain portions of the coarser pegmatites crystallized at lower tem- 

 peratures. In these coarser pegmatites the graphic intergrowths of 

 quartz and feldspar crystallized above 575° C, while the coarser and 

 more siliceous portions characterized by cavities, and probably richer 

 in gaseous or fluid constituents, crystallized below 575°. Since 



I Edson S. Bastin, "Feldspar and Quartz Deposits of Southeastern New York," 

 Bull. U.S. Geol. Survey No. Jij, 395-98. 



