fenner: babingtonite from passaic county 553 



prehnite, datolite, or pectolite. Among other minerals some 

 indication of their presence may at times be found, but often 

 they have been filled with later minerals and their outlines have 

 been more or less obliterated. The mineral which formerly 

 occupied the cavities evidently occurred most frequently in radi- 

 ating groups, sometimes extending from a centre in various 

 directions, sometimes assuming a rather flattened or fan-like 

 form. A length of 3 or 4 inches is not uncommon, "and in 

 one instance the impressions of a group of fan-like crystals w*as 

 observed, which measured S^ inches (21.5 cm.) in length and 7| 

 inches (19 cm.) in greatest breadth. Apparently a considerable 

 portion of the centre of the group had been broken away, so that 

 the original length was probably 3 or 4 inches greater. In cross- 

 section the casts of individual crystals are either lozenge-shaped 

 or nearly rectangular. Both forms are often associated in the 

 same hand-specimen. 



In an article^ which the present writer published several years 

 ago it was shown that the various minerals which are found 

 in these deposits exhibit a well-defined sequence of deposition 

 and that during earlier periods in their history the assemblage 

 of minerals differed greatly from that now found. The earliest 

 period was characterized by the formation of large quantities 

 of quartz, albite, and the mineral represented by the casts, to- 

 gether with a small amount of garnet, hematite, and sulphides. 

 The question of the nature of the mineral which had been present 

 in such abundance and had been removed was considered most 

 interesting and considerable time was given to an attempt to 

 obtain a clue to its nature. In one of the microscopic sections 

 a few small crystals of some unrecognized mineral were found, and 

 in occasional hand-specimens out of several hundred which were 

 gone over some small and almost entirely decomposed remnants 

 of the same substance were discovered. A slight description of 

 the mineral was given and from its general characteristics it 

 was considered to be a rather abnormal amphibole, perhaps 



' The Watchung Basalt aiul the Paragenseis of Its Zeolites and Other Secondary 

 Minerals; Annals N. Y. Acad. Sci., XX, 2, Pt. IT, 93-187. 1910. 



