Ferrihydrite | SSHADE

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Mineral phase

IMA name: Ferrihydrite

Class: non-silicate mineral
Compound type: oxide-hydroxide

Chemical composition

Formula: $Fe^{3+}_2O_3 \bullet 0.5(H_2O)$
Chemical formula: (Fe3+)2O3•0.5(H2O)
Elemental formula: (Fe3+)2 O3.5 H
Isotope mixture type: terrestrial abundance

	Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Fe^{3+}$	Iron(III) cation	element	2		constituent element	main
	$O$	Oxygen	element	3.5		constituent element	main
	$H$	Hydrogen	element	1		constituent element	main

Composition comments: Common impurities: ?

Oxides composition

Oxides

Formula	$Fe_{2}O_{3}$	$H_{2}O$
Mass fraction (%)	94.66	5.34

Classifications

Strunz

Class: oxides - hydroxides - arsenites (04)
Division: hydroxides (without V or U) (04.F)
Family: Hydroxides with OH, without H2O; sheets of edge-sharing octahedral (04.FE)
Code: 04.FE.35

Dana

Major class: oxides and hydroxides (III)
Class: simple oxides (04)
Type: with a cation charge of 3+ (A+++2O3) (04.03)
Group: -Ferrihydrite- group (04.03.02)
Code: 04.03.02.02

Crystallography

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

Physical properties

Molar mass: 168.70 $g/mol$
Density: 3.8 - 3.93 $g/cm^3$

Thermodynamical properties

State NTP: solid

Optical properties

Refringence type: unknown
Refringence sign: unknown
Pure color: brown
Color: yellow brown, dark brown
Diaphaneity: opaque
Luster: unknown

Links and Publications

Links