272 North — Pseudomorjphs of Limonite after Marcasite. 



is unusually smooth and hard. The crystal is 2-8 C[n wide and 

 4 ctn high. The general shape of this crystal, as well as those 

 shown in fig. 1, is of the Folkestone type (fig. 5, Dana's Sys- 

 tem of Mineralogy), though the indentations indicating twin- 

 ning are not frequent. Several loose crystals of this general 

 form were found, one of which is shown in fig. 3. Fig. 4 (nat. 

 size) shows another well-defined though smaller crystal from 

 the locality which yielded the yellow-coated specimens. This 

 crystal, as will be seen at a glance, is of the Freiberg type 

 (fig 6, Dana's System of Mineralogy), the face c being promi- 

 nent. Many of the crystals from this particular locality show 

 this same form. 



A few specimens of limonite after pyrite were picked up in 

 the same localities which yielded the pseudomorphs after mar- 

 casite. Upon another hill, at least two miles distant, a con- 

 siderable deposit of limonite after pyrite was located, and upon 

 this hill no specimens after marcasite were found. None of 

 the specimens after pyrite are in the form of pyritohedrons or 

 plain cubes, but all are cubes modified by octahedrons. 



Specimens of this new find of limonite after marcasite can 

 be seen at the National Museum in Washington, the American 

 Museum of Natural History in New York, and in the mineral 

 collections of Princeton University, Rutgers College, and the 

 Case School of Applied Science. In addition, many speci- 

 mens, including those shown in the accompanying illustrations, 

 can be seen in the author's private collection at New Bruns 

 wick. 



Rutgers College, 



New Brunswick, N. J. 



