Seamanite, named for discoverer Arthur E. Seaman, is a rare

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

boron Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron group'' it has th ...

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...

mineral with formula Mn₃ (OH)₄PO₄)(OH)₂. The yellow to pink mineral occurs as small, needle-shaped crystals. It was first discovered in 1917 from a mine in

Iron County, Michigan Iron County is a county in the Upper Peninsula of the U.S. state of Michigan. As of the 2020 Census, the population was 11,631. The county seat is Crystal Falls. History Iron County was organized in 1885, with territory partitioned from Marq ...

, United States and identified in 1930. , seamanite is known from four sites in Michigan and

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

History

In 1917, Arthur E. Seaman collected a mineral sample from the Chicagon Mine in

. He correctly believed it to be a new mineral species based on a qualitative analysis of its composition by F. B. Wilson.

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

delayed further study of the mineral until 1929. A study in 1930 proved it to be a new mineral and named it ''seamanite'' in honor of Seaman. They cited his career as a professor of geology and mineralogy and his contributions to the field as reasons for the naming.Kraus, p. 220. The original analysis of the mineral in 1930 suggested seamanite to be a hydrated salt.Kraus, p. 223–5 However, in 1971, the mineral was determined to be the

coordination compound A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...

Mn₃ (OH)₄PO₄)(OH)₂.Moore, p. 1527.

Description

Seamanite is a transparent, yellow to pink mineral that occurs as needle-shaped crystals. Seamanite is a brittle mineral with a

mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

of 4. It is found in the crevices of fractured

siliceous rock Siliceous rocks are sedimentary rocks that have silica (SiO2) as the principal constituent. The most common siliceous rock is chert; other types include diatomite. They commonly form from silica-secreting organisms such as radiolarians, diatoms, or ...

. The type occurrence was found in association with small crystals of

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

, thin coatings of

manganese oxide Manganese oxide is any of a variety of manganese oxides and hydroxides.Wells A.F. (1984) ''Structural inorganic chemistry'' 5th edition Oxford Science Publications, . These include * Manganese(II) oxide, MnO * Manganese(II,III) oxide, Mn3O4 * Man ...

, and fibrous

sussexite Sussexite is a manganese borate mineral Mn B O2( O H). Crystals are monoclinic prismatic and typically fibrous in occurrence. Colour is white, pink, yellowish white with a pearly lustre. It has a Mohs hardness of 3 and a specific gravity of 3.12. ...

.Slawson, p. 575 Seamanite has also been found with

shigaite Shigaite is a mineral with formula NaAl3(Mn2+)6(SO4)2(OH)18·12H2O that typically occurs as small, hexagonal crystals or thin coatings. It is named for Shiga Prefecture, Japan, where it was discovered in 1985. The formula was significantly revised ...

Distribution

, seamanite is known from four locations: the Cambria-Jackson Mine in

Marquette County, Michigan Marquette County ( ) is a county located in the Upper Peninsula of the U.S. state of Michigan. As of the 2020 Census, the population was 66,017. The county seat is Marquette. The county is named for Father Marquette, a Jesuit missionary. It wa ...

, the Chicagon Mine and the Bengal Mine in

, and the Iron Monarch open cut in the

Eyre Peninsula The Eyre Peninsula is a triangular peninsula in South Australia. It is bounded by the Spencer Gulf on the east, the Great Australian Bight on the west, and the Gawler Ranges to the north. Originally called Eyre’s Peninsula, it was named aft ...

, South Australia. The

type material In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes t ...

is stored at

Michigan Technological University Michigan Technological University (Michigan Tech, MTU, or simply Tech) is a public research university in Houghton, Michigan, founded in 1885 as the Michigan Mining School, the first post-secondary institution in the Upper Peninsula of Michigan. ...

Houghton, Michigan Houghton (; ) is the largest city and seat of government of Houghton County in the U.S. state of Michigan. Located on the Keweenaw Peninsula, Houghton is the largest city in the Copper Country region. It is the fifth-largest city in the Uppe ...

, and at the

National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7 ...

in Washington, D.C. as sample 96282.

Crystallography

Seamanite is formed of acicular crystals elongated along 01and showing the faces and up to one centimeter. It has an

orthorhombic crystal system 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 ...

and the ''Pbnm''

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchan ...

. The parameters of its

unit cell In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector, for example) does not necessaril ...

are: a=7.811 Å, b=15.114 Å, c=6.691 Å, Z=4 units per unit cell.

Notes

References

Bibliography

* * *Palache, P.; Berman H.; Frondel, C. (1960). "''Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. (Seventh Edition)"'' John Wiley and Sons, Inc., New York, pp. 388-389. *

External links

{{commonscat-inline, Seamanite Borate minerals Phosphate minerals Manganese(II) minerals Orthorhombic minerals Minerals in space group 62