268 F. W. Clarke — Minerals of Litchfield, Maine. 



the other massive zeolitic alterations of eleeolite which have 

 been on analytical grounds referred to the thomsonite series. 

 Hydronephelite, indeed, is directly derived from sodalite, but 

 the latter itself probably originated from elseolite; so that the 

 new species may quite properly be considered along with the 

 other zeolites which were previously mentioned. The fact 

 that it contains more potassium than the sodalite, is note- 

 worthy, and calls for an explanation which I am unfortunately 

 not prepared to offer. 



Albite and Lepidomelane. 



The albite of Litchfield, which appears to be associated with 

 other undetermined feldspars, is mostly in obscure masses. 

 Occasionally a fragment is found with a translucent cleavage 

 surface one or two centimeters broad. Such a specimen was 

 partially analyzed, giving H 2 052, Si0 2 66-39, A1 2 3 19*69, 

 K 2 0*99, ISra 2 10-17. These figures serve only for com- 

 plete identification of the species. 



The lepidomelane exists abundantly in the elgeolite rock, 

 but mostly in small black scales. Sometimes tolerably large 

 plates of it are found, black and brilliant, decidedly brittle, 

 and apparently affected by alteration. An analysis gave the 

 following results. The iron determinations were made by Mr. 

 Eiggs. 



H 2 4-62 



F none 



Ti0 2 



Si0 2 32-09 



A1 2 3 18-52 



Fe 2 3 _. 19-49 



FeO 14-10 



MnO 1-42 



MgO 1-01 



K 2 8-12 



Na.,0 -.. 1-55 



100-92 



This analysis is noteworthy on account of the extremely low 

 percentage of, silica, which is approached, so far as I can ascer- 

 tain, only in an analysis by Rammelsberg of a black mica from 

 Brevig. The ratio between silicon and oxygen is nearly 1 : 5, 

 which agrees with no known formula. My results make it 

 extremely probable that the mica is a mixture and that it has 

 undergone an alteration tending toward the ultimate develop- 

 ment of some chloritic species. Still it deserves, as also do the 

 feldspars of the locality, a more thorough examination. 



