Bog iron
Encyclopedia
Bog iron refers to impure iron
deposits that develop in bog
s or swamp
s by the chemical or biochemical oxidation of iron carried in the solutions. In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite
(FeO(OH)). It was discovered during the Pre-Roman Iron Age
, and most Viking era iron was smelted
from bog iron.
Iron-bearing groundwater typically emerges as a spring
. The iron is oxidized to ferric hydroxide upon encountering the oxic environment of the surface. Bog ore often combines goethite, magnetite
and vug
s 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 silicate
s, which can form a glassy coating that grants some resistance to rust
ing.
in Massachusetts
was drawn down by deepening the outlet channel in a search for bog iron. The Saugus Iron Works National Historic Site
, on the Saugus River
in Saugus, Massachusetts
operated between 1646 and 1668. The site contains a museum and several reconstructed buildings. The success of the Saugus Iron Works, and the rapid depletion of the region's natural bog iron, led them to send prospectors out into the surrounding countryside. In 1658 they bought 1600 acres (6.5 km²) of land which covered areas that are now Concord, Acton, and Sudbury. They set up a large production facility in Concord, Massachusetts
along the Assabet River with dams, ponds, watercourses and hearths, but by 1694 the natural bog iron there had also been exhausted, and the land was sold for farming.
The John Winthrop, Jr. Iron Furnace Site, on the National Register of Historic Places
in Quincy, Massachusetts
predated the Saugus site by a year, but on a smaller scale and with less success. Put into operation in 1645, it is considered to be the oldest iron blast furnace in the United States, although it operated for only two years.
In New Jersey
, bog ore was mined and refined in Central
& Southern
New Jersey for the production of tools and wrought iron rails (many of which still grace stairs in Trenton
and Camden
), which took advantage of its natural rust resistance. During the American Revolution
, the iron was used for cannon
balls for the American colonial forces.
Bog iron was also found on the Eastern Shore of Maryland
. The remains of a commercial smelting operation near Snow Hill, Maryland
are now a state and national historic site. Known as Furnace Town
, it was called the Nassawango Iron Furnace
after the nearby creek. The commercial furnace ran from about 1825 to 1850.
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
deposits that develop in bog
Bog
A bog, quagmire or mire is a wetland that accumulates acidic peat, a deposit of dead plant material—often mosses or, in Arctic climates, lichens....
s or swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
s by the chemical or biochemical oxidation of iron carried in the solutions. In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite
Goethite
Goethite , named after the German polymath Johann Wolfgang von Goethe, is an iron bearing oxide mineral found in soil and other low-temperature environments. Goethite has been well known since prehistoric times for its use as a pigment. Evidence has been found of its use in paint pigment samples...
(FeO(OH)). It was discovered during the Pre-Roman Iron Age
Pre-Roman Iron Age
The Pre-Roman Iron Age of Northern Europe designates the earliest part of the Iron Age in Scandinavia, northern Germany, and the Netherlands north of the Rhine River. These regions feature many extensive archaeological excavation sites, which have yielded a wealth of artifacts...
, and most Viking era iron was smelted
Smelting
Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores...
from bog iron.
Iron-bearing groundwater typically emerges as a spring
Spring (hydrosphere)
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...
. The iron is oxidized to ferric hydroxide upon encountering the oxic environment of the surface. Bog ore often combines goethite, magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
and vug
Vug
Vugs are small to medium-sized cavities inside rock that may be formed through a variety of processes. Most commonly cracks and fissures opened by tectonic activity are partially filled by quartz, calcite, and other secondary minerals. Open spaces within ancient collapse breccias are another...
s or stained quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
. Oxidation may occur through enzyme catalysis
Enzyme catalysis
Enzyme catalysis is the catalysis of chemical reactions by specialized proteins known as enzymes. Catalysis of biochemical reactions in the cell is vital due to the very low reaction rates of the uncatalysed reactions....
by iron bacteria
Iron bacteria
In the management of water-supply wells, iron bacteria are bacteria that derive the energy they need to live and multiply by oxidizing dissolved ferrous iron . The resulting ferric oxide is insoluble, and appears as brown gelatinous slime that will stain plumbing fixtures, and clothing or utensils...
. 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 silicate
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
s, which can form a glassy coating that grants some resistance to rust
Rust
Rust is a general term for a series of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture...
ing.
Colonial America
Bog iron was widely sought in colonial America. Lake MassapoagLake Massapoag
Lake Massapoag is a , natural, springfed lake located in Sharon, Massachusetts. The name Massapoag is Algonquin, meaning "large water".Massapoag is the headwater of the Canoe River, which flows south to join the Taunton River and empty into Narragansett Bay...
in Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
was drawn down by deepening the outlet channel in a search for bog iron. The Saugus Iron Works National Historic Site
Saugus Iron Works National Historic Site
Saugus Iron Works National Historic Site is a National Historic Site located about 10 miles northeast of Downtown Boston in Saugus, Massachusetts. It is the site of the first integrated ironworks in North America, 1646 – 1668...
, on the Saugus River
Saugus River
The Saugus River is a river in Massachusetts.The river is long, drains a watershed of approximately , and passes through Wakefield, Lynnfield, Saugus, and Lynn as it meanders east and south from its source in Lake Quannapowitt in Wakefield to its mouth at Boston Broad Sound...
in Saugus, Massachusetts
Saugus, Massachusetts
Saugus is a town in Essex County, Massachusetts, United States, in the Greater Boston area. The population was 26,628 at the 2010 census.-History:Saugus was first settled in 1629. Saugus is an Indian name believed to mean "great" or "extended"...
operated between 1646 and 1668. The site contains a museum and several reconstructed buildings. The success of the Saugus Iron Works, and the rapid depletion of the region's natural bog iron, led them to send prospectors out into the surrounding countryside. In 1658 they bought 1600 acres (6.5 km²) of land which covered areas that are now Concord, Acton, and Sudbury. They set up a large production facility in Concord, Massachusetts
Concord, Massachusetts
Concord is a town in Middlesex County, Massachusetts, in the United States. As of the 2010 census, the town population was 17,668. Although a small town, Concord is noted for its leading roles in American history and literature.-History:...
along the Assabet River with dams, ponds, watercourses and hearths, but by 1694 the natural bog iron there had also been exhausted, and the land was sold for farming.
The John Winthrop, Jr. Iron Furnace Site, on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
in Quincy, Massachusetts
Quincy, Massachusetts
Quincy is a city in Norfolk County, Massachusetts, United States. Its nicknames are "City of Presidents", "City of Legends", and "Birthplace of the American Dream". As a major part of Metropolitan Boston, Quincy is a member of Boston's Inner Core Committee for the Metropolitan Area Planning Council...
predated the Saugus site by a year, but on a smaller scale and with less success. Put into operation in 1645, it is considered to be the oldest iron blast furnace in the United States, although it operated for only two years.
In New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, bog ore was mined and refined in Central
Howell Works
Howell Works was a bog iron-based production facility for pig iron which was established in New Jersey in the early 19th century by American engineer and philanthropist James P. Allaire...
& Southern
Batsto Village, New Jersey
Batsto Village is a New Jersey Historic site located in Wharton State Forest in the south central Pine Barrens, and a part of the Pinelands National Reserve. It is listed on the New Jersey and National Register of Historic Places, and is administered by the New Jersey Department of Environmental...
New Jersey for the production of tools and wrought iron rails (many of which still grace stairs in Trenton
Trenton, New Jersey
Trenton is the capital of the U.S. state of New Jersey and the county seat of Mercer County. As of the 2010 United States Census, Trenton had a population of 84,913...
and Camden
Camden, New Jersey
The city of Camden is the county seat of Camden County, New Jersey. It is located across the Delaware River from Philadelphia, Pennsylvania. As of the 2010 United States Census, the city had a total population of 77,344...
), which took advantage of its natural rust resistance. During the American Revolution
American Revolution
The American Revolution was the political upheaval during the last half of the 18th century in which thirteen colonies in North America joined together to break free from the British Empire, combining to become the United States of America...
, the iron was used for cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
balls for the American colonial forces.
Bog iron was also found on the Eastern Shore of Maryland
Eastern Shore of Maryland
The Eastern Shore of Maryland is a territorial part of the U.S. state of Maryland that lies predominately on the east side of the Chesapeake Bay and consists of nine counties. The origin of term Eastern Shore was derived to distinguish a territorial part of the State of Maryland from the Western...
. The remains of a commercial smelting operation near Snow Hill, Maryland
Snow Hill, Maryland
Snow Hill is a town in Worcester County, Maryland, United States. The population was 2,409 at the 2000 census. It is the county seat of Worcester County.-History:...
are now a state and national historic site. Known as Furnace Town
Furnace Town Living Heritage Museum
The Old Furnace Town Heritage Museum is an outdoor museum near Snow Hill Maryland that uses a living history format with live demonstrations to re-create a vanished 19th century community. The museum contains various historic buildings, including most importantly the Nassawango Iron Furnace, an...
, it was called the Nassawango Iron Furnace
Nassawango Iron Furnace Site
The Nassawango Iron Furnace was built in 1830 by the Maryland Iron Company to produce iron from bog ore deposits in its vicinity. It is notable for its innovative use of a "hot blast" technique for smelting the iron, which had only been developed in England around 1828, and which may have been...
after the nearby creek. The commercial furnace ran from about 1825 to 1850.
See also
- LimoniteLimoniteLimonite is an ore consisting in a mixture of hydrated iron oxide-hydroxide of varying composition. The generic formula is frequently written as FeO·nH2O, although this is not entirely accurate as limonite often contains a varying amount of oxide compared to hydroxide.Together with hematite, it has...
- Iron ore
- Ore genesisOre genesisThe various theories of ore genesis explain how the various types of mineral deposits form within the Earth's crust. Ore genesis theories are very dependent on the mineral or commodity....
- Acidithiobacillus ferrooxidansAcidithiobacillusAcidithiobacillus is a genus of Proteobacteria. Like all Proteobacteria, Acidithiobacillus is Gram-negative. The members of this genus used to belong to Thiobacillus, before they were reclassified in the year 2000....
(iron oxidizing bacteria) - History of ferrous metallurgyHistory of ferrous metallurgyThe history of ferrous metallurgy began far back in prehistory. The earliest surviving iron artifacts, from the 5th millennium BC in Iran and 2nd millennium BC in China, were made from meteoritic iron-nickel. It is not known when or where the smelting of iron from ores began, but by the end of the...
External links
- Hurstwic: Iron Production in the Norse Era
- Talzhemir's Bog Iron Page
- Bog Iron Industry in The Pinelands, New Jersey
- ironfurnaces.com - a free wiki dedicated to the preservation of iron furnaces
- Bog Iron Formation in the Nassawango Watershed, Maryland U.S. Geological Survey: Open-File Report 03-346
- American Society of Mechanical Engineers, Nassawango Furnace landmark.
- ASME PDF file with detailed reconstruction drawings of the furnace and surroundings.
- Nassawango Furnace at the Maryland Historic Trust.
- “A Brief History of Nassawango Iron”
- Furnace Town, Snow Hill, Worcester County Maryland.