4:26 Whitlock — Calcite from West Pater son, N. J. 



A"rt. XXXYIII. — Some neio Crystallographic Combinations 

 of Calcite from West Pater son, Is. J. ; by H. P. Whitlock. 



The calcite crystals which furnish the material for this 

 paper were found in the trap rock quarry one mile northwest of 

 the village of Haledon, N. J. They were collected by Mr. 

 H. H. Hindshaw in the summer of 1904 and are now in the 

 collection of the New York State Museum. They are essen- 

 tially different from any of the types described by Rogers* and 

 present two forms which are new to the species. The interest 

 attached to the remarkable crystallized datolite from the local- 

 ity added to the above facts seems to justify a short crystallo- 

 graphic description of these crystals. 

 The writer wishes to express his thanks 

 to Mr. Hindshaw for the material to be 

 described, as well as for facts relating to 

 the location and geology of the locality. 

 Type I. Crystals of type I occur iso- 

 lated or in small parallel aggregates, 

 immediately associated with the light 

 greenish datolite previously described 

 from an adjacent localityf. In several 

 instances they were obtained from the 

 casts left by the flat plates of some min- 

 eral of previous generation, presumably 

 a mica, which has been dissolved out of 

 the matrix, of datolite. Minute rosettes 

 of specular hematite accompany the crys- 

 tals, of this type, aa well as a thin coating 

 of limonite. 



These crystals are 3 mm to 8 ram in vertical' 

 length, transparent and colorless. They are rhombohedral in 

 habit, _the dominant form being the negative rhombohedron 

 %.(0"9 - 9*4). This rhombohedron is modified on the polar_edges 

 by the positive rhombohedrons p. (1011) and m. (4041) in 

 small development. The positive scalenoheclron U: (5491) is 

 present as a series of small striated faces modifying the basal 

 angles of x- Fig. 1 shows this combination. 



Type II. The crystals of this type occur implanted directly 

 on the walls of the open seams and cavities in the diabase. 

 They are quite uniform in size, averaging 5 mm in vertical length 

 and are developed with the vertical axis in every instance nor- 



* A. F. Eogers, The crystallography of the Caleites of the New Jersey 

 Trap Region. School of Mines Quarterly, xxiii, 336, 1902. 



fDana, E. S., On the Datolite from Bergen Hill, New Jersey. This Jour- 

 nal (3), iv, 16, 1872. 



