H. W. Foote — Occurrence of Pollucite^ etc. 



457 



Formation. 



Basic breccia. 

 Intermediate breccias. 

 Acid breccia. 

 Agglomerates, Waterlain 



igneous material. 

 Sandstone. 



Flora. 



Lamar. 



Intermediate flora. 

 Fort Union. 

 Livingston. 



Laramie. 



Upper Miocene. 

 Lower Miocene. 

 Eocene. 

 Cretaceous. 



Cretaceous. 



In a thin bed of conglomerate exposed by the cutting of the 

 grand canyon of the Yellowstone, vertebrate remains of a 

 fossil horse were discovered, sufficient to determine the 

 Pliocene age of the deposit. Upon this conglomerate rests 

 the great body of rhyolite and the still later basalt. Soon 

 after the dying out of these recent basalts climatic conditions 

 changed and the Yellowstone Park was covered by glacial ice 

 which distinctly marked the coming in of Pleistocene time. 



Art. LI. — On the Occurrence of Pollucite, Mangano-Colum- 

 oite and Microlite at Pumford, Maine ; by H. W. Foote. 



During- the spring of 1885, Mr. E. M. Bailey of Andover, 

 Maine, sent to Prof. S. L. Penfield for identification some 

 specimens from Black Mountain, Pumford, Me. Among 

 these, one which had the appearance of ordinary white quartz 

 or beryl proved to be the very rare and interesting mineral 

 pollucite. The following summer, the locality was visited by 

 Professor Penfield accompanied by Mr. Bailey and a supply of 

 pollucite and its associated minerals was obtained. 



The minerals occur in a ledge of coarse pegmatite which has 

 been worked without success for gem tourmalines, but the 

 locality is of unusual mineralogical interest and the work has 

 been continued to some extent for specimens. In addition to 

 quartz, feldspar and mnscovite, which are crystallized on a large 

 scale, there were found pink, green and white tourmalines in 

 imbedded crystals, pink lepidolite, both granular and in crys- 

 tals, with hexagonal outline, spodumene occasionally in crys- 

 tals but usually only in cleavage masses, amblygonite rather 

 abundant and in cleavage masses only, beryl not very common, 

 cassiterite rather abundant as irregular masses and rarely in 

 small but distinct crystals, black columbite, pollucite and, very 

 rarely, mangano-columbite and microlite. 



Pollucite. 



Pollucite has previously been found in the United States at 

 Hebron, Me., where "it was discovered fyy Mr. Loren B. Mer- 



