Native metal brass, bronze, pewter, German silver, osmiridium, electrum, white gold, and silver-mercury and gold-mercury amalgam. Only gold, silver, copper and the platinum metals occur in nature in large amounts. Over geological time scales, very few metals can resist natural weathering processes like oxidation, which is why generally only the less reactive metals such as gold and platinum are found as native metals. The others usually occur as isolated pockets where a natural chemical process reduces a common compound or ore of the metal, leaving the pure metal behind as small flakes or inclusions. Non-metallic elements occurring in the native state include
Ore Raththam 1987. N. Krishnaswamy of "The Indian Express" liked the film because "most of the characters get a say, the focus shifts to each of them one time or another". He also praised the narration, dialogue, background score, camera work, and editing. Ore Raththam Ore Raththam () is a 1987 Indian Tamil-language film directed by Swarnam and written by M. Karunanidhi. The film stars Karthik, BhagyalakshmiMadhuri, Kishmu, Manorama, Pandian, Seetha, M. K. Stalin and Radha Ravi. It is based on Karunanidhi's story of the same name, which was serialised in the magazine "Kungumam". "Ore Raththam" was a story which was serialised