602 fenner: babingtonite from passaic county 



somewhat fan-like form. A specimen of pectolite showing the 

 impression of flattened crystals of this kind, and with numerous 

 small offshoots of babingtonite running into the matrix, gave 

 measurements of 4 x 5 cm. On the same specunen another 

 impression with essentially similar characteristics measured 

 2| X 5 cm. and showed a thickness of 0.5 cm. An impression 

 on quartz, with remnants of babingtonite among the laminae, 

 measured 7 x 1 x 0.5 cm., and another, likewise showing bab- 

 ingtonite, gave 7 X 3.5 x 0.3 cm. In another mode of develop- 

 ment the width and thickness of the cavities do not differ greatly 

 from each other and the crystals appear to have had a simple 

 prismatic form, whose cross-section was essentially rectangular. 

 A certain specimen which shows this type is composed of an 

 aggregate of prehnite crystals in a finger-like form, which now 

 surround a rectangular cavity running through the middle of the 

 group. The original crystal is inferred to have been babingtonite 

 because of the discovery of this material among the laminae 

 projecting from one of the surfaces of the orifice. The dimensions 

 of the cavity are 5 x 0.8 x 0.5 cm. 



These measurements indicate that the crystals of babingtonite 

 attained large dimensions. Some may have been considerably 

 larger than the measurements given, as similar cavities of larger 

 size are not infrequent, but only those have been cited in which 

 the presence of babingtonite has been detected. 



If, in cavities of this character, babingtonite had been dis- 

 covered in two or three specimens only, its presence might per- 

 haps be explained in other ways than under the supposition that 

 it represented the remnants of the crystals which filled the cavities, 

 but it has been found in repeated instances in the situations where 

 it was looked for and where it might be expected to resist for the 

 longest time the solvent action of circulating waters, and its 

 presence can hardly be regarded as fortuitous. 



In practically all specimens in which babingtonite has been 

 found in the cavities thin laminae, projecting from the walls 

 and lying parallel to the widest surfaces, are a marked char- 

 acteristic, and 'such cavities are very abundant. In certain 

 other cavities the walls are either smooth or show ridges of some- 



