Lincolnite. 



437 



whose lower part is filled with another mineral ; but never in a re- 

 verse order. The amygdaloid in which this mineral occurs is ex- 

 tremely hard, and hence the chabasie has been preserved. It is, how- 

 ever, quite difficult to obtain good specimens. 



In the amygdaloid on the east side of the greenstone range in 

 Deerfield and Greenfield, I have observed a few rather poorly char- 

 acterised radiated specimens, exceedingly resembling the Thomsonite 

 of Scotland. 



In the greenstone one mile east of the village in Deerfield, a min- 

 eral occurs, closely allied in external characters to stilbite and heu- 

 landite; and hitherto I have described it as stilbite. But in its crys- 

 talline form it differs from both those species, and indeed from any 

 known mineral. I shall, therefore, venture to describe it as new; and 

 take the liberty to dedicate it to your Excellency, as the patron of sci- 

 ence, under the name of 



LINCOLNITE. 



This mineral occurs in minute yet very distinct crystals, which are 

 right oblique angled prisms. Three trials on as many crystals with 

 the common goriometer gave the following results for the angles of 

 the bases. 



First crystal: Angles A, A, 61° 



Angles B, B, 119°. 



Second crystal : Angles A, A, 61°. 



Angles B, B, 120° 



Third crystal: Angles A, A, 61°. 



Angles B, B, 120°. 



The mean result of all the trials I have made does not vary much 

 from 60° and 120°. But this may vary from the truth half a degree; 

 I think not more. The bases are commonly bright enough for the 

 application of the reflective goniometer : not so the lateral faces. 



