Ramsdellite
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Ramsdellite (Mn4+O2) is an
orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a r ...
manganese dioxide mineral. It is relatively uncommon, and is usually found in deposits containing other manganese oxide crystals.


Name

Ramsdellite is named after the American mineralogist,
Lewis Stephen Ramsdell Lewis Stephen Ramsdell (4 June 1895 – 14 June 1975) was an American mineralogist who was a pioneer in the use of X-ray diffraction to study mineral structures. Education and career Ramsdell was born in Clinton, Michigan to Dwight and Phoeb ...
(1895–1975). Ramsdell spent almost all his career at the
University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...
as a professional mineralogist. Ramsdellite was one of the new phases he first recognized in the "black manganese oxide" minerals. It was later named in his honour by Michael Fleischer and W. E. Richmond, who fully described the mineral in 1943. The mineral is also called Groutellite.


Chemistry and crystallography

The chemical formula for Ramsdellite is MnO2. The empirical formula is Mn4+O2. Ramsdellite has the same chemistry as the more common
pyrolusite Pyrolusite is a mineral consisting essentially of manganese dioxide ( Mn O2) and is important as an ore of manganese.. It is a black, amorphous appearing mineral, often with a granular, fibrous, or columnar structure, sometimes forming reniform ...
, but is orthorhombic where pyrolusite is tetragonal. Ramsdellite belongs to the Orthorhombic
crystal system In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices. Space groups are classified into crystal systems according to their po ...
and Dipyramidal
crystal class In crystallography, a crystallographic point group is a set of symmetry operations, corresponding to one of the point groups in three dimensions, such that each operation (perhaps followed by a translation) would leave the structure of a crystal un ...
. Properties:


Classification

The Dana classification is 4.4.7.1 (simple oxides: AX2). The Hey's CIM Ref is 7.18.8 (Oxides and Hydroxides, Oxides of Mn). The
Nickel–Strunz classification Nickel–Strunz classification is a scheme for categorizing minerals based upon their chemical composition, introduced by German mineralogist Karl Hugo Strunz (24 February 1910 – 19 April 2006) in his ''Mineralogische Tabellen'' (1941). The 4th ...
is 04.DB.15a, since the metal:oxygen ratio is around 1:2 and the mineral has medium-sized cations; chains of edge-sharing octahedra. Other elements in the Ramsdellite / 04.DB.15 group are
Paramontroseite Paramontroseite (V4+O2) is a relatively rare orthorhombic vanadium oxide mineral in the Ramsdellite group. Synthetic paramontroseite may have applications in medicine, batteries and electronics. Name The name Paramontroseite is derived from the ...
: V4+O2 (15a),
Akhtenskite Akhtenskite is a manganese oxide mineral with the chemical formula of MnO2 (or: ε-Mn4+O2) that was named after the Akhtensk deposit in Russia, where it was first discovered and noted in 1979. It can be found in the Akhtensk brown ironstone deposi ...
: ε-Mn4+O2 (15b) and
Nsutite Nsutite is a manganese oxide mineral with formula: ( Mn4+1−xMn2+x O2-2x(O H)2x where x = 0.06-0.07).http://www.webmineral.com/data/Nsutite.shtml Webmineral data It is found in most large manganese deposits and was first discovered in Nsuta, Ghan ...
: (Mn4+,Mn2+)(O,OH)2 (15c).


Distribution

Ramsdellite is formed by oxidization of weathered manganese minerals such as
manganite Manganite is a mineral composed of manganese oxide-hydroxide, MnO(OH), crystallizing in the monoclinic system (pseudo-orthorhombic). Crystals of manganite are prismatic and deeply striated parallel to their length; they are often grouped togethe ...
, and is often found in deposits containing various other manganese oxides. The mineral is relatively rare. The type locality, the place where Ramsdellite was first identified, is the Lake Valley district in
Sierra County, New Mexico Sierra County is a county located in the U.S. state of New Mexico. As of the 2020 Census, the population was 11,576. Its county seat is Truth or Consequences. Geography According to the U.S. Census Bureau, the county has a total area of , of w ...
, USA. Other locations in the USA where well-characterized samples of Ramsdellite have been found are
Artillery Mountains The Artillery Mountains are a mountain range in Mohave County in western Arizona. High point of the range is Artillery Peak, above sea level. Artillery Peak is at coordinates N 34.36946 W 113.58160 . Mineral resources of the Artillery Mountains ...
, Arizona; Mistake mine,
Yavapai County, Arizona Yavapai County is near the center of the U.S. state of Arizona. As of the 2020 United States census, 2020 census, its population was 236,209, making it the fourth-most populous county in Arizona. The county seat is Prescott, Arizona, Prescott. ...
; Idarado mine, near
Telluride, Colorado Telluride is the county seat and most populous town of San Miguel County in the southwestern portion of the U.S. state of Colorado. The town is a former silver mining camp on the San Miguel River in the western San Juan Mountains. The first ...
; and Monroe-Tener mine, near Chisholm, Minnesota. Good samples have been found in Canada along the East River in
Pictou County, Nova Scotia Pictou County is a county in the province of Nova Scotia, Canada. It was established in 1835, and was formerly a part of Halifax County from 1759 to 1835. It had a population of 43,657 people in 2021, a decline of 0.2 percent from 2016. Furthermo ...
; in Mexico in Los Gavilanes,
Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
; In India in Dongari Buzurg,
Bhandara Bhandara () is a city and municipal council which serves the administrative headquarters of eponymous administrative Bhandara Taluka and Bhandara district in the state of Maharashtra, India. It is connected with NH-53 and NH-247. Overview ...
, Maharashtra; in Australia in the Iron Monarch quarry,
Iron Knob Iron Knob is a town in the Australian state of South Australia on the Eyre Peninsula immediately south of the Eyre Highway. At the 2006 census, Iron Knob and the surrounding area had a population of 199. The town obtained its name from its prox ...
, South Australia; in Japan in the Otoshibetsu and Tanno mines,
Hokkaido is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The la ...
; in the Czech Republic at
Horní Blatná Horní Blatná (german: Bergstadt Platten) is a town in Karlovy Vary District in the Karlovy Vary Region of the Czech Republic. It has about 400 inhabitants. The town centre is well preserved and is protected by law as urban monument zone. Histor ...
; in Germany at Bütten-Adenstadt,
Lower Saxony Lower Saxony (german: Niedersachsen ; nds, Neddersassen; stq, Läichsaksen) is a German state (') in northwestern Germany. It is the second-largest state by land area, with , and fourth-largest in population (8 million in 2021) among the 16 ...
and Clara Mine, near
Oberwolfach Oberwolfach ( gsw, label= Low Alemannic, Obberwolfä) is a town in the district of Ortenau in Baden-Württemberg, Germany. It is the site of the Oberwolfach Research Institute for Mathematics, or Mathematisches Forschungsinstitut Oberwolfach. Ge ...
, Black Forest; in Egypt at Gebel To Yu, Yoider, and Um Bogna; and in South Africa at Hotazel, near
Kuruman Kuruman is a small town with just over 53,000 inhabitants in the Northern Cape province of South Africa. It is known for its scenic beauty and the Eye of Kuruman, a geological feature that brings water from deep underground. The abundance of water ...
, Northern Cape. Ramsdellite is found in the manganese deposits near
Moanda Moanda is one of the largest towns in Gabon, lying on the N3 road in Haut Ogooué. It is also one of the most important manganese mining towns in the world, under the auspices of the ''Compagnie Minière de l'Ogooué'' (COMILOG), which began ...
, Haut-Ogooué Province, Gabon, mined by the
Compagnie minière de l'Ogooué The Compagnie minière de l'Ogooué, or COMILOG, is a manganese mining and processing company based in Moanda, Gabon. It is a subsidiary of the French metallurgical group Eramet. The company is the world's second largest producer of manganese ore. ...
. These deposits were formed by supergene enrichment of
Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
sediments.


Notes


Sources

* * * * * * * {{DEFAULTSORT:Ramsdellite Manganese(IV) minerals Orthorhombic minerals Minerals in space group 62 Oxide minerals