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While iron is the most abundant element on Earth, most of this iron is concentrated in the inner and outer cores. [43] [44] The fraction of iron that is in Earth's crust only amounts to about 5% of the overall mass of the crust and is thus only the fourth most abundant element in that layer (after oxygen, silicon, and aluminium). [45]
In chemistry, "iron group" used to refer to iron and the next two elements in the periodic table, namely cobalt and nickel.These three comprised the "iron triad". [1] They are the top elements of groups 8, 9, and 10 of the periodic table; or the top row of "group VIII" in the old (pre-1990) IUPAC system, or of "group VIIIB" in the CAS system. [5]
In terms of mass, iron is the fourth most common element within the Earth's crust. It is found in many minerals, such as hematite, magnetite, and taconite. Iron is commercially produced by heating these minerals in a blast furnace with coke and calcium carbonate. [2] Ruthenium is a very rare metal in Earth's crust.
Elemental iron is virtually absent on the Earth's surface except as iron-nickel alloys from meteorites and very rare forms of deep mantle xenoliths.Although iron is the fourth most abundant element in Earth's crust, composing about 5% by weight, [4] the vast majority is bound in silicate or, more rarely, carbonate minerals, and smelting pure iron from these minerals would require a prohibitive ...
Iron-60 has a half-life of 2.6 million years, [12] [13] but was thought until 2009 to have a half-life of 1.5 million years. It undergoes beta decay to cobalt-60 , which then decays with a half-life of about 5 years to stable nickel-60.
The oldest known iron objects used by humans are some beads of meteoric iron, made in Egypt in about 4000 BC. The discovery of smelting around 3000 BC led to the start of the Iron Age around 1200 BC [15] and the prominent use of iron for tools and weapons. [16] Recognised as an element by Guyton de Morveau, Lavoisier, Berthollet, and Fourcroy ...
The iron compounds produced on the largest scale in industry are iron(II) sulfate (FeSO 4 ·7H 2 O) and iron(III) chloride (FeCl 3). The former is one of the most readily available sources of iron(II), but is less stable to aerial oxidation than Mohr's salt ((NH 4) 2 Fe(SO 4) 2 ·6H 2 O). Iron(II) compounds tend to be oxidized to iron(III ...
Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, but easy to oxidize. [11] Manganese and its common ions are paramagnetic. [12] Manganese tarnishes slowly in air and oxidizes ("rusts") like iron in water containing dissolved oxygen. [13]