78 JOURNAL OF THE 



occurrence (as yet) of fluid- bearing masses. Otherwise the local- 

 ity is similar to that of Rutherford ton. 



From a careful study of the rock in situ and of luauy speci- 

 mens from tlie localities, I am forced to conclude that these forms 

 of quartz are pseudomo)-plis of the interstices between crystals of 

 some mineral that crystallized in thin flat tabular forms. 



Sections of these water-bcMring forms present an interior of 

 bright transparent crystals, or of mammillary chalcedony; while 

 the structure of the walls is semi-radiated from the exterior. 

 Careful examination of the surfaces show a series of triangular 

 markings (angles 60°) on all sides. Now these mai'kings are 

 exactly what w-e would expect by the slow deposition of quartz on 

 the basal pinacoid of a uniaxal crystal (rhombohedral), or of the 

 deposition of quartz from solution in a vein filled up with 

 meshed and netted crystals which being thin, presented only 

 basal planes for contact surfaces. What the original mineral 

 was is not shown by the specimens. Tlie casts of crystal cavi- 

 ties in the larger masses show an unmistakable hexagonal prism 

 with a large development of the basal pinacoid (these two planes 

 identified by striations on the quartz), and this characteristic is 

 persistent. 



A careful test by Mr. J. B. Mackintosh of the fluid contents 

 of a small four-sided crystal (?) proved it to be only neutral 

 water, and the bubble to be only air (not carbonic acid gas as 

 was expected). 



It is to be hoped that at do distant day deep work at one of 

 these localities will discover specimens of the tliin hexagonal 

 plates, which have left only the interstices between them in the form 

 of a mould of quartz. 



For the use of the figures of crystals, included in the forego- 

 ing pages, I extend to the editors of the American Journal of 

 Science mv sincere thanks. 



