Iodine is a chemical element with symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at a standard conditions that sublimes readily to form a violet gas. The elemental form was discovered by the French chemist Bernard Courtois in 1811.
Definition of CHOLLA. : any of numerous shrubby opuntias chiefly of the southwestern United States and Mexico that have needlelike spines partly enclosed in a papery sheath and cylindrical joints âcalled also cholla cactus.
CHRYSOCOLLA, (Cu,Al)2H2Si2O5(OH)4Â·nH2O. A. Chrysocolla, upper left, (width - 8.7 cm) from Inspiration Mine, Globe, Arizona. Arizona-Sonora Desert Museum. (Â© photo by Jeffrey A. Scovil). B. Chrysocolla, middle, coating on cuprite (height - 4.5 cm) from the Allouez mine, Allouez, Michigan. Seaman Museum, Michigan Technological University. (Â© photo by John Jaszczak). C. Drusy chrysocolla, upper right, (width-ca. 2.5 cm) from unnamed locality, Arizona.