LEE PERO GIA Gai PROVINCE OF ESSE COUNLY. 7-93 
1862 in the granite of Swampscott, was reported from several 
places in Maine and Massachusetts by Iddings and Cross,* while 
Sears? has added a number of localities to the list. 
A small grain of. pink fluorite was seen in the granite from 
Squam Light, and colorless grains in that from Pigeon Hill 
quarry, Cape Ann. I could identify no danalite, which Shaler 
speaks of as rare and resembling garnet in thin sections. 
For chemical analysis a typical fresh specimen was chosen 
from the large pit of the Rockport Granite Co.’s quarry, a 
hornblende-biotite-granite; sp. gr. 2.618 at 18° C. There is 
given for comparison an analysis already published? of the 
riebeckite-granite of Quincy, described by T. G. White.+ 
I I I II 
SiO, - - = 7720 HEO3 BaO_ - - oie iaeen none 
IOS - - 0.25 0.18 Na Oki - 3.80 4.66 
Al,O; - - I1.94 2 e2 K,O - - - 4.98 4.63 
Fe,0O3 - - 0.55 2.91 Hie OCs —)) = trace Soke 
FeO - = a eOLO 7 Te5i5 HO (iro7—) Ee etOw23 0.41 
MnO - - trace trace Pe Oz - - 
MgO - . - trace 0.04 
CaO S 5 0.31 0.31 SP GilOO549. 1OO.G 
I Hornblende-Granite. Rockport Cape Ann, Anal. H. S. WASHINGTON. 
II Riebeckite-Granite. Quincy Blue Hills, Anal. H. S. WASHINGTON, 
The analysis of the Rockport granite is a typical one, fairly 
rich in potash, but low in lime and iron oxides. It resembles 
that of the Quincy granite, but the latter is lower in silica and 
higher in iron oxides. Although the composition of the horn- 
blende is unknown, yet as its amount is small, the mineral com- 
position can be approximately calculated as below in Ia, the 
biotite being assumed to have the composition (K,H,Fe,) 
Al, (SiO,), as given by Clarke from an analysis by Riggs.5 The 
composition of the Quincy granite calculated as already pub- 
lished is given in Ila. 
tIppincs and Cross, Am. J. Sci. (3), Vol. XXX, p. 108, 1885. 
2SEARS, Bull. Essex Inst., Vol. XXVI, p. 189, 1894. 
3H. S. WASHINGTON, Am. Jour. Sci. (4), Vol. VI, p. 181, 1898. 
47. G. WHITE, Proc. Bost. Soc. Nat. Hist., Vol. XXVIII, p. 128, 1897. 
5 CLARKE, Am. Jour. Sci. (3), Vol. XXXII, p. 360, 1886. 
