C. H. Hitchcock—Labradorite Rocks in New Hampshire. 48 
At its locality* the mineral occurs in considerable abun- 
dance, and, according to the statement of the president of the 
company, H. P. Livermore, Esq., of San Francisco, to whose 
kindness I am indebted for the material for this investigation, 
constitutes the most abundant and valuable ore of the mine. 
Art. IX.—Norian Rocks in New Hampshire; by C. H. Hircu- 
COCK, State Geologist of New Hampshire. 
ore have been brought out to enable us to form some 
idea of the different groups existing in this terra incognita. 
structure of the whole State. I refer to the discovery of mas- 
sive labradorite and the associated minerals of the Norian or 
ipper Laurentian Group. These cover an area of several 
Square miles in Waterville and Albany, adjoining towns, and 
probably occur in other parts of the State also. Whether the 
various gneisses, granites, felsites and jaspers in this part of the 
mountains, all differing from anything found elsewhere in the 
State, are to be assigned to the same series, remains to be proved. 
The occurrence of the labradorite in a new locality is of special 
interest at this time, when scientists are discussing the funda- 
mental question, whether certain predominant minerals in me 
tamorphic formations may be employed like fossils to indicate 
difference of geological age. : 
t the Montreal meeting (1857) of the American Associa- 
tion for the Advancement of Science, Sir W. E. ogan an- 
nounced+ that the Laurentian rocks could probably be divided 
Into two groups, dependent upon the species of feldspar present, 
the potash feldspars characterizing one, and the lime and sod 
feldspars the other portion. This position is not discussed in 
* The “ Redington Quicksilver Mine,” Lake Cousty, Calfornia. 
¢ Proc. Amer. Assoc, Ady. Sci., 1857, p. 47. 
