T. L. Walker — Tungstite and Meymacite. 305 



Art. XXXII. — A Review of the Minerals Tungstite and Mey- 

 macite • by T. L. Walker, University of Toronto. 



Earlv in the last century Silliman* described a mineral rich 

 in tungstic acid from Huntington, Connecticut, and although 

 no analysis had been made of this mineral it was agreed to 

 regard it as anhydrous tungstic acid, W0 3 . Many years later 

 Nordenskiold described the crystal form of artificially prepared 

 anhydrous tungstic acid, and this description has been incorpo- 

 rated in the general description of Silliman's mineral. Finally 

 in 1874 Carnot studied and described an occurrence of a mass- 

 ive mineral greenish to yellowish in color, very impure from 

 the presence of foreign substances and, concluding that it was 

 hydrated tungstic acid of the formula W0 3 .2H 2 0, named it 

 Meymacite and regarded it as a distinct species. The uncer- 

 tainty as to the proportion of water in the case of Carnot's 

 analyses is shown by the fact that in his three analyses the 

 water percentage varied from 6'85 to 12*93. Meymacite has 

 usually been regarded as a variety of tungstite. Recently, 

 while examining some specimens from British Columbia, the 

 writer had occasion to review the relationship of these min- 

 erals. Material from the vicinity of Salmo occurring in small 

 masses in gold quartz veins, and at times containing small par- 

 ticles of native gold, appeared on examination with the blow- 

 pipe to agree fairly well with the standard description of 

 tungstite. This was followed by a detailed examination, which 

 leads to the conclusion that it is at once the same as the mate- 

 rial of Silliman and of Carnot and that the chemical compo- 

 sition is W0 3 .H 2 0. In the following description the main 

 characteristics of the British Columbia mineral are recorded. 



General Description. — The material here considered reached 

 the Mineralogical Museum of the University of Toronto 

 through the kindness of Mr. R. B.Thomson, lecturer in botany 

 in the University of Toronto. Later, on visiting British 

 Columbia in 1907, more specimens were obtained, but as the 

 vein from which the specimens came was not being worked at 

 the time of my visit no considerable quantity was obtainable. 

 The specimens are made up of a heavy golden-yellow mineral 

 streaked and netted with dark strings exhibiting a structure 

 common to serpentines? In the centers of the yellow areas 

 small druses of minute crystals may be observed on examina- 

 tion with the microscope. Quartz, wolframite, scheelite and 

 specks of native gold make up a considerable portion of the 

 whole. The grain is too fine to make it possible to secure a 

 sample of pure yellow material for analysis. The yellow min- 



* This Journal (1), iv, pp. 52 and 187. 



