328 



TRANSACTIONS OF THE 



[may 17, 



is now inaccessible. Prof. James Hall, however, preserved one 

 superb crystal, that is now in the Peabod}- Museum at Yale 

 Universit}^ and that has been described and figured by E. S. 

 Dana.* 



The mining operations at Cook shaft evidently cut the pegma- 

 tite, which was thrown on the dump, where it has remained for 

 some 3'ears past. The cr3stals suitable for study and measure- 

 ment are obtained in cracking up the quartz, a lucky stroke oc- 

 casionally laying bare a promising crystal, which can then be 

 dug out. The one measured by the reflecting goniometer, as 



Fig. 2. 



tabulated below, projected into a cavity, which later became 

 filled with calcite, a rare phenomenon at this locality. Some 

 very large crystals, not yet detached from the matrix have 

 been deposited in the mineralogical collections of Columbia 

 University, one mass of pegmatite being nearly 200 lbs., and 

 largely allanite, but the crystals studied were, as a rule, :f to ^ 

 inches (6-12 mm.) long, and about the same in thickness. The 

 faces present were mostly orthodoraes, smooth but not brightly 

 lustrous. Next in abundance were prism faces, while pj^raraids 

 were rare. The small crystal referred to above, was about -^^ in. 



*See American Journal of Science, June, 1884, p. 479. System of Minernlogy, 1893, 

 p. ri22. 



