71 



The catalogue already presented, compiled by Dr. Fowler of 

 Franklin, supplies a nearly complete list of the other minerals 

 found in this part of the igneous and altered zone of rocks. 



From Franklin we may trace the white crystalline limestone 

 continuous to Sterling, about three miles to the southwest. 



Here we find it lying in contact with a remarkable vein 

 consisting exclusively of Franklinite and the red oxide of zinc ; 

 the former in crystalline granules, often approaching the ochto- 

 hedral form, invested by a paste of the zinc ore, which frequently 

 constitutes more than one-half of the mass. The position of this 

 vein is on the eastern declivity of a hill of considerable elevation, 

 where it occupies the same intermediate relation to the gneiss 

 and crystalline limestone which was mentioned of the vein at 

 Franklin. 



At Sterling, the metallic vein, where it is visible at the surface, 

 rests with a steep southeast dip covformahly upon the steeply- 

 dipping beds of gneiss, rising in the form of a bold clift" or wall 

 along the side of the hill. Against this wall of ore, and at the 

 base of the hill, repose the beds of the white altered limestone, 

 presenting unequivocal traces of its original planes of stratification, 

 showing the sedimentary origin of the rock. It obviously dips 

 at the same inclination of from 70° to 80° to the southeast, with 

 the vein and the gneiss upon which it lies. 



The metalliferous vein is from eight to ten feet in thickness, 

 and consists of no other minerals but the Franklinite and ore of 

 zinc. From its exposed position on the flank of the hill, the ore 

 could be excavated to an almost indefinite extent with a facility 

 unusual in the history of mining operations. Zinc of an admirably 

 pure quality has been prepared from this ore by Mr. Hitz, under 

 the directions of Mr. Hasler, for the manufacture of the brass 

 for the standard weights and measures now making by the latter 

 scientific gentleman for the several custom-houses of the United 

 States, by order of Congress. An economical method for the 

 separation of the zinc from the Franklinite in this ore, still 

 remains, however, a desideratum in practical metallurgy. 



Between Sterling and Sparta, the belt of crystalline limestone 

 is traceable with but little interruption nearly the whole distance, 

 affording in some places specimens of a variegated marble of 



