Beauinoutite^ Linculaite^ and Heulandlte. 425 



in the crystals of this mineral from Faroe, I have never ob- 

 served among the specimens from either of the localities here 

 referred to, nor from any locality in the United States.* 



To remove all doubt as to the identity of the two minerals, 

 I requested Mr. J. E. Teschemacher to separate some of the 

 best crystals from my Baltimore specimens, and subject them 

 to measurement by the reflecting goniometer, as I well knew 

 the public would have the fullest confidence in his use of that 

 instrument. He has informed me that P on P gives 90'', M 

 on T 130% M on a 143" 17^ P on a 111° 58^ and adds that 

 he has no doubt the mineral is Heulandite. The variation in 

 the third measurement was owing to the imperfection of 

 the surface. We have, therefore, every reason for believing 

 that the specific nature of the Beaumontite of M. Levy, can 

 no longer be maintained. It is proper to add, that the same 

 name, in honor of a distinguished French naturalist, Elie de 

 Beaumont, had already been applied to another mineral from 

 Chessy, in France, described and analyzed by my friend. Dr. 

 Charles T. Jackson. f 



Lincolnite. — Prof. Hitchcock, in his Final Report % on the 

 Geohs^ical Survey of Massachusetts, has given the description 

 of a mineral found in the vicinity of Deerfield, which he has 

 named in honor of the late governor of this State. Unfortu- 

 nately, it must share the same fate with Beaumontite, though 

 it seems less entitled to the distinction of a new species ; for 

 in every respect but one, viz. its not being replaced on the 

 obtuse solid angles by the planes a, as shown in fig. 1, it is 

 impossible to discover any dissimilarity between this mineral 

 and Heulandite ; both exhibiting the same characters before 

 the blowpipe, the same color, lustre, hardness, etc. The 

 crystals of Lincolnite are very small, usually requiring a 

 microscope in their examination, and they have their acute 

 lateral edges replaced by very narrow planes ^/^. corresponding 

 in their measurement with Heulandite. But, according to 



* See fig. 2 in Phillips's Mineralogy', Allan's edition, p. 25. 

 t American Journal of Science, Vol. xxxvii. p. 398. 

 t Final Report &,c., p. 662. 



47 



