348 



DESCRIPTIVE MINERALOGY. 



Geological Situation. It occurs in cavities and veins in trap and greenstone, along with 

 others of the zeolite family. 



LOCALITIES. 



Epistilbite is said to occur in the greenstone at Bergen hill,* along with the other zeolitic 

 minerals found at that locality. If such is the fact, I cannot doubt that it will also be met with 

 in the greenstone and trap of Rockland. 



APOPHYLLITE. 



[Probably from its exfoliating before the blowpipe {Phillips).] 



Apophyllite. Haay, Cleaveland, Phillips, Beudant, T/umson and Shepard. — Pyramidal Zeolite, or Apophyl- 

 lite. Jameson. — Pyramidaler Kuphon-Spath. Mohs. 



Fig. 339. Description. Colour white or greyish. It occurs regularly crystal- 



lized ; also in straight and curved lamellar distinct concretions, mas- 

 sive and disseminated. The primary form is a right square prism, Fig. 

 339. Cleavage parallel with the primary faces, most perfect in the direc- 

 tion of P. Fracture uneven. Lustre internally glistening and vitreous ; 

 lateral planes of the prism shining : the terminal ones pearly. Ranges 

 from transparent to translucent. Hardness from 4 . 5 to 5 . 0. Specific gra- 

 vity from 2.20 to 2.50. Before the blowpipe it exfoliates, intumesces, 



and ultimately fuses into a white blebby glass ; with borax, it melts readily into a transparent 



globule. In nitric acid, it separates into flakes ; and when reduced to powder, becomes 



gelatinous and translucent. 



Its crystalline form, the peculiar lustre of its terminal planes, and the action of acids, will 



form sufficient grounds of distinction between apophyllite and the minerals which it resembles. 



Composition. Specimen from Greenland — Silica 51,86, lime 25.22, potash 5.31, water 

 16.90, fluoric acid trace {Stromeyer). 



Geological Situation. Apophyllite occurs in fissures in trap and greenstone, and spa- 

 ringly in the gneiss found near the pyrogenous rocks. 



localities. 



New-York County. This mineral is occasionally found in veins and cavities in green- 

 stone bowlders. It is also met with in the veins of gneiss at Harlem. 



* Bourne. Amtricm Journal ef Seienet, 



