554 fenner: babingtonite from passaic county 



arfvedsonite. Certain slight bits of evidence pointed to the Hkeh- 

 hood that this represented the mineral of the casts. 



In subsequent visits to these localities a constant watch was 

 kept for further evidence on the matter, but it was not until 

 the past summer (July, 1914) that much of value was found. 

 At that time a visit to the Francisco quarry at Great Notch 

 resulted in the discovery of a larger quantity of the mineral 

 than had been seen at any previous time. The amount was 

 still very small, the largest mass having a greatest dimension of 

 only 20 mm., and the total weight collected was probably little 

 more than a gram. The relations were such, however, as to con- 

 nect the mineral quite definitely with the casts, and it was pos- 

 sible to make determinations which showed the mineral to be 

 the rare species, babingtonite (Ca, Fe, Mn) SiOs + Fcs (8103)3. 



In several instances the small crystal-remnants found occupy 

 portions of the characteristic cavities of rectangular or lozenge- 

 shaped sections in quartz, or are intergrown in a blade-like form 

 with quartz-crystals. In almost all cases alteration has pro- 

 duced a decomposition-product on the crystal surfaces of a woolly 

 or asbestos-like material, nearly white in color, which obscures 

 the original crystal-faces. The same substance frequently 

 penetrates deeply within the crystals along cracks or cleavage 

 planes. This feature would render it very difficult to pick out 

 pure material from the small quantity of the mineral at hand in 

 sufficient amount for a satisafctory quantitative analysis, and 

 this was not attempted. It was necessary, therefore, to establish 

 its identity by other means. The unaltered material is nearly 

 black and opaque in mass, but translucent and brown or dark- 

 green in thin fragments. The lustre is shining or splendent — 

 nearly that of anthracite. 



Through the kindness of Dr. E. T. Wherry of the National 

 Museum, several specimens of babingtonite were loaned from 

 their collection and it was thus made possible to make direct 

 comparisons with undoubted material. 



In the determination of properties the material used was 

 either that from Great Notch or that in the microscopic section 

 prepared several years ago, which came from Paterson. 



