What is "bog iron"

Iron \I"ron\ ([imac]"[u^]rn), n. [OE. iren, AS. [=i]ren, [=i]sen, [=i]sern; akin to D. ijzer, OS. [=i]sarn, OHG. [=i]sarn, [=i]san, G. eisen, Icel. [=i]sarn, j[=a]rn, Sw. & Dan. jern, and perh. to E. ice; cf. Ir. iarann, W. haiarn, Armor. houarn.]

1. (Chem.) The most common and most useful metallic element, being of almost universal occurrence, usually in the form of an oxide (as hematite, magnetite, etc.), or a hydrous oxide (as limonite, turgite, etc.). It is reduced on an enormous scale in three principal forms; viz., cast iron, steel, and wrought iron. Iron usually appears dark brown, from oxidation or impurity, but when pure, or on a fresh surface, is a gray or white metal. It is easily oxidized (rusted) by moisture, and is attacked by many corrosive agents. Symbol Fe (Latin Ferrum). Atomic number 26, atomic weight 55.847. Specific gravity, pure iron, 7.86; cast iron, 7.1. In magnetic properties, it is superior to all other substances.

   Note: The value of iron is largely due to the facility with which it can be worked. Thus, when heated it is malleable and ductile, and can be easily welded and forged at a high temperature. As cast iron, it is easily fusible; as steel, is very tough, and (when tempered) very hard and elastic. Chemically, iron is grouped with cobalt and nickel. Steel is a variety of iron containing more carbon than wrought iron, but less that cast iron. It is made either from wrought iron, by roasting in a packing of carbon (cementation) or from cast iron, by burning off the impurities in a Bessemer converter (then called Bessemer steel), or directly from the iron ore (as in the Siemens rotatory and generating furnace).

2. An instrument or utensil made of iron; -- chiefly in composition; as, a flatiron, a smoothing iron, etc.

   My young soldier, put up your iron.
   --Shak.

3. pl. Fetters; chains; handcuffs; manacles.

   Four of the sufferers were left to rot in irons.
   --Macaulay.

4. Strength; power; firmness; inflexibility; as, to rule with a rod of iron.

5. (Golf) An iron-headed club with a deep face, chiefly used in making approaches, lifting a ball over hazards, etc.

   Bar iron. See Wrought iron (below).

   Bog iron, bog ore; limonite. See Bog ore, under Bog.

   Cast iron (Metal.), an impure variety of iron, containing from three to six percent of carbon, part of which is united with a part of the iron, as a carbide, and the rest is uncombined, as graphite. It there is little free carbon, the product is white iron; if much of the carbon has separated as graphite, it is called gray iron. See also Cast iron, in the Vocabulary.

   Fire irons. See under Fire, n.

   Gray irons. See under Fire, n.

   Gray iron. See Cast iron (above).

   It irons (Naut.), said of a sailing vessel, when, in tacking, she comes up head to the wind and will not fill away on either tack.

   Magnetic iron. See Magnetite.

   Malleable iron (Metal.), iron sufficiently pure or soft to be capable of extension under the hammer; also, specif., a kind of iron produced by removing a portion of the carbon or other impurities from cast iron, rendering it less brittle, and to some extent malleable.

   Meteoric iron (Chem.), iron forming a large, and often the chief, ingredient of meteorites. It invariably contains a small amount of nickel and cobalt. Cf. Meteorite.

   Pig iron, the form in which cast iron is made at the blast furnace, being run into molds, called pigs.

   Reduced iron. See under Reduced.

   Specular iron. See Hematite.

   Too many irons in the fire, too many objects or tasks requiring the attention at once.

   White iron. See Cast iron (above).

   Wrought iron (Metal.), the purest form of iron commonly known in the arts, containing only about half of one per cent of carbon. It is made either directly from the ore, as in the Catalan forge or bloomery, or by purifying (puddling) cast iron in a reverberatory furnace or refinery. It is tough, malleable, and ductile. When formed into bars, it is called bar iron.

n. (context geology English) deposits of mixed oxides and hydroxides of iron formed when iron-bearing groundwater emerges onto the surface

Bog iron is a form of impure iron deposit that develops in bogs or swamps by the chemical or biochemical oxidation of iron carried in solution. In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite (FeO(OH)).

Iron-bearing groundwater typically emerges as a spring. The iron is oxidized to ferric hydroxide upon encountering the oxidizing environment of the surface. Bog ore often combines goethite, magnetite and vugs or stained quartz. Oxidation may occur through enzyme catalysis by iron bacteria. It is not clear whether the magnetite precipitates upon first contact with oxygen, then oxidizes to ferric compounds, or whether the ferric compounds are reduced when exposed to anoxic conditions upon burial beneath the sediment surface and reoxidized upon exhumation at the surface.

Iron made from bog ore will often contain residual silicates, which can form a glassy coating that imparts some resistance to rusting.