U. S. GEOLOGICAL SURVEY 
BULLETIN NO. 229 PL. VII 
A. THIN SECTION OF LU X U LI AN IT E FROM EAR MOUNTAIN. 
Magnified 80 diameters: a, tourmaline; b, groundrrass of secondary calcite. 
> 
»** 
•^ * 
K"S» 
i -\.Ti 
. -^ V > 
•<r*i 
d 
J?. POLISHED SURFACE OF TIN ORE FROM LOST RIVER. 
a, Cassiterite; b, gray pyrite; C, zinnwaldite mica; <J fluorite; e, groundmass of fluorite and calcite; /, ground- 
mass, chiefly kaolin. 
