 Platinum is one of the least reactive metals . It has remarkable resistance to corrosion , even at high temperatures , and is therefore considered a noble metal . Consequently , platinum is often found chemically uncombined as native platinum . Because it occurs naturally in the alluvial sands of various rivers , it was first used by pre @-@ Columbian South American natives to produce artifacts . It was referenced in European writings as early as 16th century , but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists . 
