BY W. F. PETTERD, C.M.Z.S. 195 



than the granite enclosing them to the process of weather- 

 ing, and therefore stand out in relief upon the exposed 

 faces of the rock. The nodules usually show a radial 

 arrangement of their constituents. Those areas in the 

 granite in which these nodules are developed carry the 

 stanniferous lodes." (L. K. Ward.) 



This mineral, which characterises a common modifica- 

 tion of the acid rocks, more notably near the selvage of 

 contact, or may more rarely permeate rocks adjacent 

 to the granite, and whose presence depends upon the actual 

 introduction of boron and fluorine emanations, has been 

 obtained in the vicinity of Mt. Lyell, at a locality in 

 proximity to the original mine workings, on what is now 

 the property of the Mt. Lyell Mining Company ; but the 

 exact spot cannot now be detected. It was reported to 

 afford a remarkably high assay return for gold, but that, 

 judging from the specimens now in collections, is open to 

 doubt. It occurs as a closely interwoven, fibrous, and 

 matted mass of a dark-green colour, throughout which 

 are interspersed patches and irregular granulary milk- 

 w^hite quartz. The tourmaline, both green and brown, 

 is often in the form of extremely fine, almost micro, hemi- 

 hedral needles which not rarely show a distinctly divergent 

 and radiating grouping, the needles often embedded and 

 penetrating the quartz granules. The general colouration 

 and character of the occurrence separate it from any 

 other known form of the species occurring in the island, 

 although it has some resemblance to that so abundant at 

 the Stanley River, and still more distinctly to the well- 

 known occurrence at Mt. Bischoff. 



As tourmaline has not previously been recorded from 

 Mt. Lyell or vicinity, the occurrence is of some special 

 interest. It may be noted that the distinctly acid mineral 

 molybdenite has been detected, but in extremely small 

 quantity, on the Lyell Tharsis Mine, which is in the neigh- 

 bourhood of the reputed locality from which the specimens 

 of tourmaline now in question were obtained, and about 

 which occurrence no doubt can exist. 



332. TuNGSTiTE (Tungsten Trioxide). 



Occurs as pulverulent, earthy, and, more rarely, semi- 

 crystallised patches and bands of a more or less intense 

 yellow colour. It is commonly adherent to and coating 

 wolframite, from the decomposition of which it is derived. 

 Ben Lomond. It has occurred with wolframite and scheel- 

 ite in a quartz matrix at the North Pieman Heads. 



