U. S. GEOLOGICAL SURVEY 



BULLETIN 583 PLATE VIII 



A. CRYSTALLIZED FERBERITE FROM THE "CROW PATENT," NEDERLAND, COLO. 



The crystals are attached by the C axis and show penetration twins and reentrant angles. Coated with 

 ammonium chloride. Natural size. 



B. CRYSTALLIZED FERBERITE FROM THE GEORGIA A. MINE, NEDERLAND, COLO. 

 Coated with ammonium chloride. X 10. 



