304 Mr Haidinger on Two Newly determined Species 



Sectile. Thin laminae, slightly flexible. 



Hardness = 2.0 . . . 2.5, exactly the same as in the hemis- 

 prismatic ; here also the face of perfect cleavage admits of 

 being scratched by rock-salt. The two species scratch each 

 other mutually. Sp. Gr. = 2.848, of several fragments of 

 crystalline coats. 



Observations. 

 A specimen, containing both the species described above, 

 forms one among the numerous interesting objects which the 

 mineralogist admires in the cabinet of Mr Ferguson of Raith. 

 It was there placed with gypsum, to which, in fact, it is very 

 nearly allied in regard to form and general appearance, and 

 described in the following manner on a ticket accompanying 

 it : — " Selenite X en prismes tetraedres tronques en biseau, 

 et en hexaedres, dont ni les faces ni les troncatures son pro- 

 noncees distinctement (quelques uns des x X son deja decom- 

 poses et changes en platre) sur du quarz x, qui pose sur 

 une croute tres mince ondulee brune de calcedoinne, celle 

 ci sur une autre d'argil verte, celle si sur une autre de bary- 

 te rouge, dans le centre de laquelle se trouve un fragment 



de petrosilex gris, de ." As there is no locality given, 



I am the more particular in quoting the exact orthography 

 of the ticket, as it may perhaps be of use in enabling some 

 mineralogist, who happens to be acquainted with that kind of 

 descriptions, to trace the specimen to its original source. The 

 description itself will, however, require some farther comment. 

 The crystals of " selenite'''' are those of the hemiprismatic 

 gypsum haloide, the first of the two species described above, 

 some of which are nearly half an inch long, and a line in 

 thickness It is very likely not an entirely new species, but 

 a variety of pharmacolite, now observed for the first time in 

 crystals large enough both to admit of measurement, and to 

 allow the characters derived from hardness and specific gra- 

 vity to be ascertained to a considerable degree of exactness. 

 The pharmacolite itself cannot be called a species which we 

 know, since the whole of our information respecting its na- 

 tural-historical properties is confined to its occurring in 

 exceedingly delicate white capillary crystals, aggregated in 



