native elements

Of the 92 chemical elements found in nature, only 19 are known to occur as minerals uncombined with other elements (excluding elements that occur as atmospheric gases). These native elements are commonly divided into three groups—namely, metals (chromium, iron, copper, zinc, silver, tin, platinum, osmium, iridium, gold, mercury, lead); semimetals (bismuth, antimony, arsenic, tellurium, selenium); and nonmetals (sulfur, carbon). The crystalline structure of these metals is usually either cubic close-packed or hexagonal-packed, while the semimetals and nonmetals have structures that are more complex. Several native elements have one or more polymorphic forms whose occurrence depends on the conditions of formation. Carbon, for example, may occur naturally as graphite or diamond.