Constituent Coquimbite | SSHADE

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Constituent

Name: Coquimbite
IMA name: Coquimbite

Class: non-silicate mineral
Compound type: sulfate

Constituent abundance in material

Relevance: main - minor
Arrangement: in multi-phases
Mass fraction: 0.01 $\pm$ 0.1

Chemical composition

Formula: $Fe^{3+}_2(SO_4)_3 \bullet 9(H_2O)$
Chemical formula: (Fe3+)2(SO4)3•9(H2O)
Elemental formula: (Fe3+)2 S3 O15 (O-)6 H18
Isotope mixture type: terrestrial abundance

	Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Fe^{3+}$	Iron(III) cation	element	2		constituent cation	main
	$(SO_4)^{2-}$	Sulfate anion	chemical function	3		anionic radical	main
	$H_2O$	Water	molecule	9		hydration	main

Chemical functions and bonds

Chemical functions

	Function	Number	Relevance
	$(SO_4)^{2-}$	3
	$R-OH$	2	main

Chemical bonds

	Bond	Number	Relevance
	$-O-H$	2	main
	$\dddot - \dddot - \dddot - S \dddot - O^{-1/2}$	4

Oxides composition

Oxides

Formula	$Fe_{2}O_{3}$	$H_{2}O$	$SO_{3}$
Mass fraction (%)	28.41	28.85	42.74

Classifications

Strunz

Class: sulfates - chromates - molybdates - tungstates (07)
Division: sulfates (selenates, etc.) without additional anions, with H2O (07.C)
Family: with only medium-sized cations (07.CB)
Code: 07.CB.50

Dana

Major class: sulfates, chromates, selenates (VI)
Class: hydrated acid and sulfates (29)
Type: where (A)2(XO4)3.x(H2O) (29.08)
Group: -Coquimbite- group (29.08.03)
Code: 29.08.03.01

Phase type: crystalline

Crystallography

Crystal system: trigonal
Crystal class: ditrigonal-scalenohedral
Crystal class symbol: -3m (D3d)
Crystal spacegroup: P-31c

Physical properties

Molar mass: 562.02 $g/mol$
Density: 2 - 2.1 $g/cm^3$

Optical properties

Refringence type: uniaxial
Refringence sign: positive
Birefringence: 0.007
Refraction index $n_{\alpha}$: 1.55
Refraction index $n_{\beta}$: 1.557
Color: greenish white, bluish white, light violet, yellowish white, brownish white
Diaphaneity: transparent
Luster: vitreous