Amarantite

{{Short description|Sulfate mineral}} {{Infobox mineral | name = Amarantite | boxwidth = | boxbgcolor = | image = Amarantite - Javir-e-Sagand, Yazd Province, Iran.jpg | imagesize = 260px | alt = | caption = | category = Sulfate minerals | formula = Fe3+2O(SO4)2·7H2O |IMAsymbol=Ama<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 = | strunz = 7.DB.30 | dana = | system = Triclinic | class = Pinacoidal ({{overline|1}}) (same H-M symbol) | symmetry = ''P''{{overline|1}} | unit cell = a = 8.9, b = 11.56 c = 6.64 [Å]; α = 95.55° β = 90.52°, γ = 97.42°; Z = 2 | color = Amaranth-red to brownish red, orange-red | colour = | habit = As radiating or matted aggregates of needles; may be columnar or bladed | twinning = | cleavage = Perfect on {010} and {100} | fracture = | tenacity = Brittle | mohs = {{frac|2|1|2}} | luster = Vitreous | streak = Lemon-yellow | diaphaneity = Transparent | gravity = 2.189–2.286 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.516 nβ = 1.598 nγ = 1.621 | birefringence = δ = 0.105 | pleochroism = X = colorless; Y = pale yellow; Z = reddish brown | 2V = Measured: 30° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = <ref name=HBM>[https://rruff.info/doclib/hom/amarantite.pdf Amarantite in the Handbook of Mineralogy]</ref><ref name=mindat /><ref name=Webmin/> }}

'''Amarantite''' is an amaranth-red to brownish mineral with the general formula of Fe3+2O(SO4)2·7H2O<ref name=HBM/><ref name=mindat /> or Fe3+SO4(OH)·3H2O.<ref name=Webmin/>

The name comes from the Greek word αμάραντος which means amaranth, an imaginary undying red flower, in allusion to its color.<ref name=Webmin>[https://webmineral.com/data/Amarantite.shtml Amarantite data on Webmineral]</ref>

Amarantite is triclinic, which means crystallographically, it has only one symmetry fold. It must be rotated 360 degrees to be exactly the same. Due to it being triclinic it falls into the biaxial optical class, the axis degrees do not equal 90 degrees and the sides of each axis are not the same length.<ref name=Alpers>Alpers, C.N., Jember, J.L. and, Nordstrom, D.K.(2000) ''Reviews in Mineralogy and Geochemistry'' (volume 40) ''Sulfate Minerals: Crystallography, Geochemisrty, and Environmental Significance''</ref> Amarantite is anisotropic,<ref name=mindat >[http://www.mindat.org/min-182.html Amarantite on Mindat.org]</ref> which means, the velocity of light varies with crystallographic direction, and there is more than one refractive index.<ref name=klein >Klein, C. and C. S. Hurlbut, Jr. (1985) ''Manual of Mineralogy,'' Wiley, 20th ed., p. 236 {{ISBN|0-471-80580-7}}</ref>

Amarantite is a very rare mineral and can only be found in a couple of places such as Carocoles, Chile. Although it is a source of iron, there is not enough amarantite to be mined for iron. However, when found in crystal form its red orange color gives it value as a collector's item.<ref name=Alpers/>

==References== {{commons category}} {{Reflist}}

* Palache, C., Berman, H., & Frondel, C. (1951), ''The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana,'' Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 611-613.

Category:Iron(III) minerals Category:Sulfate minerals Category:Triclinic minerals Category:Minerals in space group 2