Amarantite

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title: "Amarantite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["iron(iii)-minerals", "sulfate-minerals", "triclinic-minerals", "minerals-in-space-group-2"] description: "Sulfate mineral" topic_path: "general/iron-iii-minerals" source: "https://en.wikipedia.org/wiki/Amarantite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Sulfate mineral ::

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

Field	Value
name	Amarantite
image	Amarantite - Javir-e-Sagand, Yazd Province, Iran.jpg
imagesize	260px
category	Sulfate minerals
formula	Fe3+2O(SO4)2·7H2O
IMAsymbol	Ama
strunz	7.DB.30
system	Triclinic
class	Pinacoidal ()
(same H-M symbol)
symmetry	P
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
habit	As radiating or matted aggregates of needles; may be columnar or bladed
cleavage	Perfect on {010} and {100}
tenacity	Brittle
mohs
luster	Vitreous
streak	Lemon-yellow
diaphaneity	Transparent
gravity	2.189–2.286
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°
references
::

| 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 | molweight = | strunz = 7.DB.30 | dana = | system = Triclinic | class = Pinacoidal () (same H-M symbol) | symmetry = P | 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 = | 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 =

Amarantite is an amaranth-red to brownish mineral with the general formula of Fe3+2O(SO4)2·7H2O or Fe3+SO4(OH)·3H2O.

The name comes from the Greek word αμάραντος which means amaranth, an imaginary undying red flower, in allusion to its color.

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. Amarantite is anisotropic, which means, the velocity of light varies with crystallographic direction, and there is more than one refractive index.

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.

References

• 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.

References

1. Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
2. [https://rruff.info/doclib/hom/amarantite.pdf Amarantite in the Handbook of Mineralogy]
3. [https://webmineral.com/data/Amarantite.shtml Amarantite data on Webmineral]
4. 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''
5. [http://www.mindat.org/min-182.html Amarantite on Mindat.org]
6. Klein, C. and C. S. Hurlbut, Jr. (1985) ''Manual of Mineralogy,'' Wiley, 20th ed., p. 236 {{ISBN. 0-471-80580-7

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