ZEOLITES. 163 



fore the blowpipe, and readily by its association with iolite, 

 and its large hexagonal forms, with brittle folia. 



Obs. Occurs with iolite in granite at Haddam, Ct., and 

 at Unity, N. H. The iolite and chlorophyllite are often in- 

 terlarninated, and the latter appears to result from the alter- 

 ation of the former, in which the principal change is the 

 addition of water. A variety from Brevig, in Norway, has 

 been called esmarkite. The fahlunite is from Fahlun, Swe- 

 den. 



The name chlorophyllite, given to this species by Dr. 

 Jackson, is derived from the Greek chloros, green, and phuU 

 Ion, leaf. 



Pinite includes the alkaline varieties of altered iolite. The 

 cleavage is often indistinct. Color gray to grayish green. 

 Occurs in Auvergne, in decomposed feldspar-porphyry, and 

 at Schneeberg, in Saxony. 



The following species, like chlorophyllite in crystallization, appear 

 also to have proceeded from the alteration of iolite. 



Gigantolite. Color greenish to dull steel gray. Gr=2.85 — 2-88. 

 From Tamela, Finland. Iberite is near gigantolite. Color pale grayish 

 green. Gr=289. Hydrous iolite of Bonsdorf, differs from chlorophyllite 

 in containing one per cent, more of water. 



Aspasiohte is another hydrous mineral allied to the above, and found 

 associated with iolite. It usually resembles a light green serpentine, 

 and occurs in six-sided prisms. 



ZEOLITE FAMILY. 



Note. — The following species from heulandite to chaba- 

 zite, inclusive, constitute what has been called the zeolite 

 family, so named because the species generally melt and intu- 

 mesce before the blowpipe, the term being derived from the 

 Greek zeo, to boil. They consist essentially of silica, alum- 

 ina and some alkali, with more or less water. The most of 

 them gelatinize in acids, owing* to the separation of the 

 silica in a gelatinous state. 



They occur filling cavities in rocks, constituting narrow 

 seams, or implanted on the surface, and rarely in imbed- 

 ded crystals ; and never disseminated through the body of 



rock like crystals of garnet or tourmaline. All occur 



What is the meaning of the word zeolite 1 What is the constitution 

 f the zeolites ? their mode of occurrence '} 



