668 WATSON AND STEIGER : SPINELLITE FROM VIRGINIA 



THE ORE BODIES 



From developments thus far made, the emery ore bodies are 

 quite similar. in mode of occurrence to many titaniferous mag- 

 netites in gabbroic rocks and to the Virginia nelsonites. They 

 form sharply defined vein-like masses or lenses which range up to 

 6 feet across, with the greatest length thus far exposed in prospect- 

 ing of more than 120 feet. They may occur either in the granite 

 aplite-pegmatite or in the schist near the granite aplite-pegmatite 

 contact. In either case the much greater resistance of the ore 

 to weathering than that of the inclosing rocks has resulted in 

 the surface being heavily littered with large and small masses 

 of the emery. 



Contacts of the ore with fresh granite have nowhere been ob- 

 served, since the openings are shallow and are confined to the 

 residual decayed product of the granite. Along the margins of 

 the ore bodies there is usually abundant chlorite up to several 

 inches in thickness. The chlorite may exhibit a rude vertical 

 banding, the bands of which sometimes alternate with similar 

 ones of ore, limited in all cases to marginal positions in the ore 

 bodies thus far developed. Chlorite occurs also in bunchy form 

 in the ore usually distributed through the marginal portions of 

 the ore body; and, as a rule, is absent from the other parts of the 

 rich massive ore bodies but may be an important constituent of 

 the lean ones. Indeed a characteristic feature of the rich mas- 

 sive emery bodies is their freedom from micaceous (chloritic) 

 minerals so common to emery of many localities. Chlorite is 

 similarly associated with the ore bodies occurring in schist. On 

 weathering the chlorite is removed and characteristic pitted 

 surfaces are developed in the ore. 



The ore bodies in the schists are genetically related to the 

 granite aplite-pegmatite and are formed very near to the schist- 

 granite contact. They range from mere stringers a small frac- 

 tion of an inch thick to veinlike bodies or lenses 5 or 6 feet across. 

 They conform closely with the foliation of the schists, although 

 exceptionally they cut across the schist structure. In the open- 

 ings thus far made the schists are in an advanced stage of decay, 



