378 Review of Dana's Mineralogy. 



of lateral, pearly or greasy to imperfectly vitreous. Color green or 

 greenish, greenish-brown — dark olive-green. Translucent to subtrans- 

 lucent. Folia neither flexible nor elastic ; brittle. 



" Composition, according to Jackson, (communicated to the author,) 

 and Erdmann, (Jahresb. 1841, 174,) 



Chlorophyllite. Esmarkite, Brevig. 



Silica, 45-20 4597 



Alumina, 27-60 32-08 



Magnesia, 9-60 10-32 



Protoxyd of iron * 8-24 3-83 



Protoxyd of manganese, 4-08 0-41 



Water, 3-60=98.32, J. 5-49=98-10, E. 



" Traces of phosphoric acid were detected in the chlorophyllite. 



" This mineral is closely allied to the hydrous iolite of BonsdorfF, but 

 contains less water. Like that, it is found associated with iolite. Yields 

 water before the blowpipe, and becomes bluish-gray, but fuses only on 

 the edges. With carbonate of soda, effervescence takes place, and an 

 opaque greenish enamel is formed, which becomes darker green in 

 the reducing flame. 



" Obs. Chlorophyllite is usually associated with iolite in granite, and 

 appears to proceed from the alteration of iolite. It often forms thin 

 folia interlaminated with plates of iolite in the hexagonal prisms of this 

 mineral. 



" The chlorophyllite of Jackson occurs abundantly in large prismatic 

 and tabular crystals at Neal's mine in Unity, Maine, associated with 

 hornblende rocks containing iron and copper pyrites. The same mine- 

 ral occurs with iolite at Haddam, Connecticut, and has been called 

 Pinite. The Esmarkite of Erdmann is found in granite near Brevig in 

 Norway. 



" The name Chlorophyllite, given this species by Dr. Jackson, is de- 

 rived from x^ b) Q°s, green, and cpvllov, leaf, and alludes to its structure 

 and color. The name Esmarkite was previously appropriated to a 

 variety of Datholite. 



" It is probable that both the hydrous iolite of Bonsdorff and chloro- 

 phyllite have proceeded from the alteration of iolite, and the hexagonal 

 forms the crystals present may have been derived from the original 

 iolite, instead of being the actual crystallization of the hydrous mineral. 

 Gigantolite, Pinite, and Fahlunite, may also be altered forms of other 

 minerals, and probably of iolite." (pp. 306, 307.) 



* If the iron in these analyses was protoxyd, why should the sum of the alu- 

 mina and iron be equal ? (3591 and 35.84, diff. -07.) We would suggest a query if 

 it is not peroxide. — B. S., Jr. 



