Seamanite

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title: "Seamanite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["borate-minerals", "phosphate-minerals", "manganese(ii)-minerals", "orthorhombic-minerals", "minerals-in-space-group-62"] description: "Rare manganese boron phosphate mineral" topic_path: "general/borate-minerals" source: "https://en.wikipedia.org/wiki/Seamanite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Rare manganese boron phosphate mineral ::

::data[format=table title="Infobox mineral"]

Field	Value
name	Seamanite
category	Borate minerals
boxwidth	280px
image	Seamanite-zr17a.jpg
imagesize	260px
caption	Seamanite crystals on a rock sample
(5 x 4 x 3 cm)
formula	Mn3B(OH)4(OH)2
IMAsymbol	Sem
molweight	372.64 g/mol
strunz	6.AC.65
dana	43.4.5.1
system	Orthorhombic
class	Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
symmetry	Pbnm
unit cell	a = 7.811 Å, b = 15.114 Å
c = 6.691 Å, Z = 4
color	yellow, yellow-brown, pink
habit	acicular
cleavage	distinct on {001}
fracture	brittle
tenacity	brittle
mohs	4
luster	vitreous
refractive	nα = 1.640,
nβ = 1.663,
nγ = 1.665
birefringence	δ = 0.025
2V	≈40°
dispersion	weak
fluorescence	none
streak	white
gravity	3.08
density	3.08–3.128 g/cm3
solubility	in cold, dilute acids
diaphaneity	transparent
references
::

| name = Seamanite | category = Borate minerals | boxwidth = 280px | boxbgcolor = | image = Seamanite-zr17a.jpg | imagesize = 260px | caption = Seamanite crystals on a rock sample (5 x 4 x 3 cm) | formula = Mn3B(OH)4(OH)2 | IMAsymbol = Sem | molweight = 372.64 g/mol | strunz = 6.AC.65 | dana = 43.4.5.1 | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Pbnm | unit cell = a = 7.811 Å, b = 15.114 Å c = 6.691 Å, Z = 4 | color = yellow, yellow-brown, pink | habit = acicular | twinning = | cleavage = distinct on {001} | fracture = brittle | tenacity = brittle | mohs = 4 | luster = vitreous | polish = | refractive = nα = 1.640, nβ = 1.663, nγ = 1.665 | opticalprop = | birefringence = δ = 0.025 | 2V = ≈40° | dispersion = weak | pleochroism = | fluorescence= none | absorption = | streak = white | gravity = 3.08 | density = 3.08–3.128 g/cm3 | melt = | fusibility = | diagnostic = | solubility = in cold, dilute acids | diaphaneity = transparent | other = | references = Seamanite, named for discoverer Arthur E. Seaman, is a rare manganese boron phosphate mineral with formula Mn3B(OH)4(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, United States and identified in 1930. , 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

The original analysis of the mineral in 1930 suggested seamanite to be a hydrated salt. However, in 1971, the mineral was determined to be the coordination compound Mn3B(OH)4(OH)2.

Description

Seamanite is a transparent, yellow to pink mineral that occurs as needle-shaped crystals. Seamanite has also been found with shigaite.

Distribution

, 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.

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.

Crystallography

::figure[src="https://upload.wikimedia.org/wikipedia/commons/c/c4/Structure_cristalline_seamanite.png" caption="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.

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.

References

1. Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
2. "Seamanite Mineral Data". Webmineral.
3. "Seamanite". Mindat.
4. Kraus, p. 222
5. "Seamanite". Mineral Data Publishing.
6. |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.Kraus, p. 220.
7. Kraus, p. 223–5
8. Moore, p. 1527.
9. "Seamanite – Photo Gallery". Mindat.

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