48 Graham — Pseudomorphs in Me Gill TJn iversity Collection. 



only a slight trace of water is given off on heating in a closed 

 tube. The finely powdered mineral is insoluble in acids, and a 

 preliminary examination of the solution obtained after fusion 

 with a mixture of sodium and potassium carbonates showed 

 that it contained no fluorine or chlorine. An analysis was 

 made of material selected from some of the freshest crystals 

 with the following result (column I): 



RiO, 





Templeton. 

 I. 



... 63-12 



.. 19-83 



Weissig. 

 II. 



65-00 



Orthoclase, 

 III. 



64-7 



Al O 



19-54 



. 18-4 



FeO, 



._. 0-67 



0-19 





CaO 









MgO 



__ 0'24__ 



1-61 



12-69 





K 



)"■'■■ 



. 15-13 



... 16-9 



2 



Na 2 

 Li 2 

 Ism. . 



.._ 0-52 



,_. 0-S9 



0-56 



0-35 















100-40 99-94 100-0 



The sodium and lithium, which are present in only very 

 small amount, were not separately determined, but the pres- 

 ence of both was shown by a spectroscopic examination of a 

 solution in hydrofluoric acid. In containing a small percent- 

 age of lithium, this occurrence resembles the original weissigite 

 from Dresden, the result of an analysis of which by Jenzsch is 

 given above for comparison (column II). 



The crystals are therefore pseudomorphs of orthoclase after 

 laumontite and the compact material in which they are 

 embedded doubtless had a like origin. 



Although such pseudomorphs have not been described before 

 from a Canadian locality they have been found in several 

 other districts, and the following account of some of these 

 occurrences is taken mainly from Blum's treatise on pseudo- 

 morphs.* 



In 1853, Jenzschf examined a mineral which occurs at 

 Weissig, near Dresden, and which he found to have the com- 

 position of an orthoclase with a content of about one-half a per 

 cent of lithia (see his analysis quoted above) as well as the gen- 

 eral characters of a feldspar, the hardness being 6 and the 

 specific gravity 2*55 : these facts, together with the character- 

 istic form of the crystals, combinations of monoclinic prism 

 with basal plane, led Jenzsch to regard the mineral as a dis- 

 tinct species, to which he gave the name weissigite in refer- 

 ence to the locality at which it occurs. Weissigite, however, 



* Die Pseudomorphosen, II, 20 ; III, 60. 



|N. Jahrb. f. Min., 396, 1853; 405, 1854; 800, 1855. 



