Traditional metal working in Mexico more. Important metal working centers include Taxco for silver, Santa Clara del Cobre for copper, Celaya for tin and Zacatecas for wrought iron. Metal working in Mesoamerica, especially of silver, gold and copper was advanced by the time the Spanish arrived, mostly concentrated in the modern states of Michoacán, Oaxaca and Guerrero. The mining and working of metals probably came to Mesoamerican cultures from the south. Metal working was principally in gold, silver, tin and lead, with some copper work known in what is now Michoacán. Gold was generally obtained in powder or pellet form in rivers and streams from
Ceramic discharge metal-halide lamp discharge is contained in a ceramic tube, usually made of sintered alumina, similar to what has been used in the high pressure sodium lamp. During operation, the temperature of this ceramic tube can exceed 1200 kelvins. The ceramic tube is filled with mercury, argon and metal-halide salts (for example, sodium iodide). Because of the high wall temperature, the metal halide salts are partly vaporized. Inside the hot plasma, these salts are dissociated into metallic atoms and iodine. The metallic atoms are the main source of light in these lamps, creating a bluish light that is close to daylight with a