{{Short description|Rare manganese boron phosphate mineral}} {{Infobox mineral | name = Seamanite | category = Borate minerals | boxwidth = 280px | boxbgcolor = | image = Seamanite-zr17a.jpg | imagesize = 260px | caption = Seamanite crystals on a rock sample<br />(5 x 4 x 3 cm) | formula = Mn<sub>3</sub>[B(OH)<sub>4</sub>](PO<sub>4</sub>)(OH)<sub>2</sub><ref name=mindat/> | IMAsymbol = Sem<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | molweight = 372.64 g/mol<ref name=webmineral>{{cite web|title=Seamanite Mineral Data|url=https://www.webmineral.com/data/Seamanite.shtml |publisher=Webmineral |access-date=April 13, 2012}}</ref> | strunz = 6.AC.65<ref name=webmineral/> | dana = 43.4.5.1<ref name=mindat/> | system = Orthorhombic | class = Dipyramidal (mmm) <br/>H-M symbol: (2/m 2/m 2/m)<ref name=handbook /> | symmetry = ''Pbnm'' | unit cell = a = 7.811 Å, b = 15.114 Å <br/>c = 6.691 Å, Z = 4 | color = yellow, yellow-brown, pink<ref name=mindat>{{cite web|title=Seamanite|url=http://www.mindat.org/min-3599.html|publisher=Mindat|access-date=April 13, 2012}}</ref> | habit = acicular<ref name=webmineral/> | twinning = | cleavage = distinct on {001}<ref name=handbook/> | fracture = brittle<ref name=webmineral/> | tenacity = brittle<ref name=handbook/> | mohs = 4<ref name=mindat/> | luster = vitreous<ref name=webmineral/> | polish = | refractive = n<sub>α</sub> = 1.640, <br/>n<sub>β</sub> = 1.663,<br/> n<sub>γ</sub> = 1.665<ref name=K222/> | opticalprop = | birefringence = δ = 0.025<ref name=mindat/> | 2V = ≈40°<ref name=K222>Kraus, p. 222</ref> | dispersion = weak<ref name=mindat/> | pleochroism = | fluorescence= none<ref name=webmineral/> | absorption = | streak = white<ref name=webmineral/> | gravity = 3.08<ref name=mindat/> | density = 3.08–3.128 g/cm<sup>3</sup><ref name=handbook/> | melt = | fusibility = | diagnostic = | solubility = in cold, dilute acids<ref name=mindat/> | diaphaneity = transparent<ref name=handbook/> | other = | references = <ref name=handbook>{{cite web|title=Seamanite|url=https://www.handbookofmineralogy.org/pdfs/seamanite.pdf|work=Handbook of Mineralogy|publisher=Mineral Data Publishing|access-date=April 13, 2012}}</ref> }} '''Seamanite''', named for discoverer Arthur E. Seaman, is a rare manganese boron phosphate mineral with formula Mn<sub>3</sub>[B(OH)<sub>4</sub>](PO<sub>4</sub>)(OH)<sub>2</sub>. The yellow to pink mineral occurs as small, needle-shaped crystals. It was first discovered in 1917 from a mine in Iron County, Michigan, United States and identified in 1930. {{As of|2012}}, seamanite is known from four sites in Michigan and South Australia.
==History== In 1917, Arthur E. Seaman collected a mineral sample from the Chicagon Mine in Iron County, Michigan.{{#tag:ref|Some sources list it as the Chicagoan Mine<ref name=webmineral/>|group=lower-alpha|name=mine_name}} 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 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.<ref name=K220>Kraus, p. 220.</ref>
The original analysis of the mineral in 1930 suggested seamanite to be a hydrated salt.<ref name=K223_5>Kraus, p. 223–5</ref> However, in 1971, the mineral was determined to be the coordination compound Mn<sub>3</sub>[B(OH)<sub>4</sub>](PO<sub>4</sub>)(OH)<sub>2</sub>.<ref name=M60>Moore, p. 1527.</ref>
==Description== Seamanite is a transparent, yellow to pink mineral that occurs as needle-shaped crystals.<ref name=webmineral/> Seamanite is a brittle mineral with a mohs hardness of 4.<ref name=mindat/> It is found in the crevices of fractured siliceous rock.<ref name=K220/> The type occurrence was found in association with small crystals of calcite, thin coatings of manganese oxide,<ref name=K220/> and fibrous sussexite.<ref name=S575>Slawson, p. 575</ref> Seamanite has also been found with shigaite.<ref>{{cite web|title=Seamanite – Photo Gallery|url=http://www.mindat.org/gallery.php?cform_is_valid=1&min=3599&cf_pager_page=1|publisher=Mindat|access-date=April 13, 2012}}</ref>
==Distribution== {{As of|2012}}, seamanite is known from four locations: the Cambria-Jackson Mine in Marquette County, Michigan, the Chicagon Mine and the Bengal Mine in Iron County, Michigan, and the Iron Monarch open cut in the Eyre Peninsula, South Australia.<ref name=mindat/>
The type material is stored at Michigan Technological University in Houghton, Michigan, and at the National Museum of Natural History in Washington, D.C. as sample 96282.<ref name=handbook/>
==Crystallography== [[File:Structure cristalline seamanite.png|thumb|350px|Crystal structure of seamanite:<br />gray:H red:O green:B violet:Mn center of yellow tetrahedrons:P]] Seamanite is formed of acicular crystals elongated along [001] and showing the faces {110} and {111} up to one centimeter. It has an orthorhombic crystal system and the ''Pbnm'' space group. The parameters of its unit cell are: a=7.811 Å, b=15.114 Å, c=6.691 Å, Z=4 units per unit cell.<ref name=handbook/>
==Notes== {{Reflist|group=lower-alpha}}
==References== {{Reflist}}
===Bibliography=== *{{cite journal|last1=Kraus|first1=E.H.|last2=Seaman|first2=W.A.|last3=Slawson|first3=C.B.|title=Seamanite, a new manganese phospho-borate from Iron County, Michigan|journal=American Mineralogist|date=June 1930|volume=15|issue=6|pages=220–225|publisher=Mineralogical Society of America|url=http://www.minsocam.org/ammin/AM15/AM15_220.pdf|access-date=April 13, 2012}} *{{cite journal|last1=Moore|first1=Paul B.|last2=Ghose|first2=Subrata|title=A Novel Face-Sharing Octahedral Trimer in the Crystal Structure of Seamanite|journal=American Mineralogist|publisher=Mineralogical Society of America|date=September–October 1971|volume=56|issue=9 & 10|pages=1527–1538|url=http://www.minsocam.org/ammin/am56/am56_1527.pdf|access-date=April 13, 2012}} *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. *{{cite journal|last=Slawson|first=Chester B.|title=Sussexite from Iron County, Michigan|journal=American Mineralogist|publisher=Mineralogical Society of America|date=December 1934|volume=19|issue=12|pages=575–578|url=http://www.minsocam.org/ammin/AM19/AM19_575.pdf|access-date=April 13, 2012}}
==Further reading== *{{cite journal|last1=Huminicki|first1=Danielle M.C.|last2=Hawthorne|first2=Frank C.|title=Hydrogen Bonding in the Crystal Structure of Seamanite|journal=The Canadian Mineralogist|year=2002|volume=40|issue=3|pages=923–928|url=https://rruff.geo.arizona.edu/doclib/cm/vol40/CM40_923.pdf|access-date=April 14, 2012|doi=10.2113/gscanmin.40.3.923}} *{{cite journal|last1=McConnell|first1=Duncan|last2=Pondrom|first2=Walter L. Jr.|title=X-ray Crystallography of Seamanite|journal=American Mineralogist|publisher=Mineralogical Society of America|date=July 1941|volume=26|issue=7|pages=446–447|url=http://www.minsocam.org/ammin/AM26/AM26_446.pdf|access-date=April 13, 2012}}
==External links== {{commonscat-inline|Seamanite}}
Category:Borate minerals Category:Phosphate minerals Category:Manganese(II) minerals Category:Orthorhombic minerals Category:Minerals in space group 62