 Platinum is an extremely rare metal , occurring at a concentration of only 0 @.@ 005 ppm in Earth 's crust . It is sometimes mistaken for silver ( Ag ) . Platinum is often found chemically uncombined as native platinum and as alloy with the other platinum @-@ group metals and iron mostly . Most often the native platinum is found in secondary deposits in alluvial deposits . The alluvial deposits used by pre @-@ Columbian people in the Chocó Department , Colombia are still a source for platinum @-@ group metals . Another large alluvial deposit is in the Ural Mountains , Russia , and it is still mined . 
