Cronstedtite | SSHADE

Processing math: 100%

Mineral phase

IMA name: Cronstedtite

Class: silicate mineral
Compound type: phyllosilicate

Chemical composition

Formula: $Fe^{2+}_2Fe^{3+}.(SiFe^{3+})O_5(OH)_4$
Chemical formula: (Fe2+)2(Fe3+)(SiFe3+)O5(OH)4
Elemental formula: (Fe2+)2 (Fe3+)2 Si O9 H4
Isotope mixture type: terrestrial abundance

	Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Fe^{2+}$	Iron(II) cation	element	2		constituent element	main
	$Fe^{3+}$	Iron(III) cation	element	2		constituent element	main
	$Si$	Silicon	element	1		constituent element	main
	$O$	Oxygen	element	9		constituent element	main
	$H$	Hydrogen	element	4		constituent element	main

Composition comments: Common impurities: Al, Ca

Chemical functions and bonds

Chemical functions

	Function	Number
	$(OH)^-$	4

Chemical bonds

	Bond	Number
	$O^--H$	1

Oxides composition

Oxides

Formula	$FeO$	$Fe_{2}O_{3}$	$SiO_{2}$	$H_{2}O$
Mass fraction (%)	35.97	39.97	15.04	9.02

Classifications

Strunz

Class: silicates (09)
Division: phyllosilicate (09.E)
Family: with kaolinite layers composed of tetrahedral and octahedral nets (09.ED)
Code: 09.ED.15

Dana

Major class: silicates (VIII)
Class: phyllosilicate sheets of six-membered rings (71)
Type: with 1:1 layers (71.01)
Group: Serpentine group (Amesite subgroup) (71.01.02c)
Code: 71.01.02c.07

Crystallography

Phase type: crystalline
Crystal system: trigonal
Crystal class: ditrigonal-pyramidal
Crystal class symbol: 3m (C3v)
Crystal spacegroup: P31m

Physical properties

Molar mass: 399.50 $g/mol$
Density: 3.34 - 3.35 $g/cm^3$

Thermodynamical properties

State NTP: solid

Optical properties

Refringence type: biaxial
Refringence sign: negative
Birefringence: 0.080
Refraction index $n_{\alpha}$: 1.72
Refraction index $n_{\beta}$: 1.8
Refraction index $n_{\gamma}$: 1.8
Dispersion V: moderate, r < v
Pure color: black
Color: black, greenish black, brownish black, dark brown
Diaphaneity: transparent to translucent
Luster: vitreous

Links and Publications

Links