as a constituent of many Rocks. Ill 



In almost every instance the allanite is perfectly fresh and 

 unaltered Macroscopic crystals are occasionally seen to be 

 reddish brown in color, with a more or less deeply stained zone 

 surrounding them. In one partially decomposed rock, a transi- 

 tion of allanite to epidote is indicated by crystals of the former 

 enclosing scattered grains of epidote in such a manner as to 

 leave little doubt that they result from an alteration of the 

 enclosing mineral. 



It is interesting finally to notice how extensively allanite is 

 disseminated in minute quantities through rocks of a great 

 variety of types and from widely separated localities. With- 

 out undertaking any special investigation of the matter we 

 have found it microscopically in metamorphic rocks, in older 

 crystalline eruptive masses and in glassy lavas; in hornblende 

 gneiss and mica gneiss, in granite, granite porphyry, quartz 

 porphyry, diorite, porphyrite, andesite (glassy), dacite, and rhy- 

 olite ; and from localities in the States of Maine, Massachusetts, 

 Ehode Island, Colorado and Nevada, and the Territories of 

 Wyoming and Utah. Below is appended a list of the rocks 

 and localities alluded to, which will no doubt be greatly en- 

 larged by other observers. 



Gneiss. — Utah : Ogden Canon ; Farmington Canon, Wahsatch. 

 Wyoming: Medicine Bow Range. 

 Nevada: Clover Canon, B. Humboldt Mountains. 



Granite. — Maine : Vinalhaven, Biddeford, Wayne, Fox 

 Island, Harrington. 

 Massachusetts : Lynnfield. 

 Rhode Island : Westerly. 

 Utah : Little Cottonwood Canon. 

 Nevada : Eureka. 



Granite porphyry. — Utah : Tooele. 



Nevada : Eureka. 



Quartz porphyry. — Colorado : Mosquito Range, Park County ; 

 Eagle River, Eagle County. 



Diorite. — Nevada: Truckee Canon. 



Porphyrite. — Colorado: Mount Silverheels, Park County; 

 Mosquito gulch, Park County ; Ten Mile Dis- 

 trict, Summit County. 

 Utah : Henry Mountains. 



Andesite {glassy). — Nevada : Eureka. 



Dacite. — Nevada: Eureka, Shoshone Park ; Washoe. 

 Utah: White Rock Mountain. 



Rhyohte. — Nevada: Eureka. 



