Iron
Of all metals iron is the most important. The pure metal is found only in such rare instances as in the case of meteorites which have fallen from space. In South America and elsewhere isolated masses of soft malleable iron have been found loose upon the surface of the earth, and these too would seem to owe their origin to the same meteoric source. In these specimens of native metallic iron nickel is usually found. The presence of iron in an oxidized condition is universal: rocks and soils are colored by it, plants contain it, as also does the blood of the human body. Pure iron is very soft and tough, has a specific gravity of 7.8, is white, and has a perfect lustre. It may be observed that there always exists a very distinct fibrous texture in good bar-iron after it has been attacked with acid; the perfection of this fibre is what gives it strength. See MALLEABLE IRON; CAST IRON; STRENGTH OF MATERIALS.