Constituent opal

Experiment NIR spectra of a series of opal (-A and -CT) in ambient conditions and at low temperature (~ -35°C) and/or low pressure (~ 8 mbar)

Sub-Experiment opal-A 86.2: Tamb, low T, low P

Sub-Experiment NIR spectra of opal-A 86.2 in ambient conditions

Spectrum NIR spectrum of opal-A 86.2 under ambient conditions Spectrum NIR spectrum of opal-A 86.2 under ambient conditions

Sub-Experiment NIR spectra of opal-A 86.2 at low temperature

Spectrum NIR spectrum of opal-A 86.2 at low temperature Spectrum NIR spectrum of opal-A 86.2 at low temperature

Sub-Experiment NIR spectra of opal-A 86.2 at low pressure

Spectrum NIR spectrum of opal-A 86.2 at low pressure Spectrum NIR spectrum of opal-A 86.2 at low pressure

Sub-Experiment opal-A 785: Tamb, low T, low P

Sub-Experiment NIR spectra of opal-A 785 in ambient conditions

Spectrum NIR spectrum of opal-A 785 under ambient conditions Spectrum NIR spectrum of opal-A 785 under ambient conditions

Sub-Experiment NIR spectra of opal-A 785 at low temperature

Spectrum NIR spectrum of opal-A 785 at low temperature Spectrum NIR spectrum of opal-A 785 at low temperature

Sub-Experiment NIR spectra of opal-A 785 at low pressure

Spectrum NIR spectrum of opal-A 785 at low pressure Spectrum NIR spectrum of opal-A 785 at low pressure

Sub-Experiment opal-A 1040: Tamb, low T, low P

Sub-Experiment NIR spectra of opal-A 1040 in ambient conditions

Spectrum NIR spectrum of opal-A 1040 under ambient conditions Spectrum NIR spectrum of opal-A 1040 under ambient conditions

Sub-Experiment NIR spectra of opal-A 1040 at low temperature

Spectrum NIR spectrum of opal-A 1040 at low temperature Spectrum NIR spectrum of opal-A 1040 at low temperature

Sub-Experiment NIR spectra of opal-A 1040 at low pressure

Spectrum NIR spectrum of opal-A 1040 at low pressure Spectrum NIR spectrum of opal-A 1040 at low pressure

Sub-Experiment opal-CT 521: Tamb, low T

Sub-Experiment NIR spectra of opal-CT 521 in ambient conditions

Spectrum NIR spectrum of opal-CT 521 under ambient conditions Spectrum NIR spectrum of opal-CT 521 under ambient conditions

Sub-Experiment NIR spectra of opal-CT 521 at low temperature

Spectrum NIR spectrum of opal-CT 521 at low temperature Spectrum NIR spectrum of opal-CT 521 at low temperature

Sub-Experiment opal-CT 1085: Tamb, low T, low P

Sub-Experiment NIR spectra of opal-CT 1085 in ambient conditions

Spectrum NIR spectrum of opal-CT 1085 under ambient conditions Spectrum NIR spectrum of opal-CT 1085 under ambient conditions

Sub-Experiment NIR spectra of opal-CT 1085 at low temperature

Spectrum NIR spectrum of opal-CT 1085 at low temperature Spectrum NIR spectrum of opal-CT 1085 at low temperature

Sub-Experiment NIR spectra of opal-CT 1085 at low pressure

Spectrum NIR spectrum of opal-CT 1085 at low pressure Spectrum NIR spectrum of opal-CT 1085 at low pressure

Sub-Experiment opal-A 1543a: Tamb, low T

Sub-Experiment NIR spectra of opal-CT 1543a in ambient conditions

Spectrum NIR spectrum of opal-CT 1543a under ambient conditions Spectrum NIR spectrum of opal-CT 1543a under ambient conditions

Sub-Experiment NIR spectra of opal-CT 1543a at low temperature

Spectrum NIR spectrum of opal-CT 1543a at low temperature Spectrum NIR spectrum of opal-CT 1543a at low temperature

Sub-Experiment opal-CT 1543b: Tamb, low T, low P

Sub-Experiment NIR spectra of opal-CT 1543b in ambient conditions

Spectrum NIR spectrum of opal-CT 1543b under ambient conditions Spectrum NIR spectrum of opal-CT 1543b under ambient conditions

Sub-Experiment NIR spectra of opal-CT 1543b at low temperature

Spectrum NIR spectrum of opal-CT 1543b at low temperature Spectrum NIR spectrum of opal-CT 1543b at low temperature

Sub-Experiment NIR spectra of opal-CT 1543b at low pressure

Spectrum NIR spectrum of opal-CT 1543b at low pressure Spectrum NIR spectrum of opal-CT 1543b at low pressure

Sub-Experiment opal-CT 1543d: Tamb, low T, low P

Sub-Experiment NIR spectra of opal-CT 1543d in ambient conditions

Spectrum NIR spectrum of opal-CT 1543d under ambient conditions Spectrum NIR spectrum of opal-CT 1543d under ambient conditions

Sub-Experiment NIR spectra of opal-CT 1543d at low temperature

Spectrum NIR spectrum of opal-CT 1543d at low temperature Spectrum NIR spectrum of opal-CT 1543d at low temperature

Sub-Experiment NIR spectra of opal-CT 1543d at low pressure

Spectrum NIR spectrum of opal-CT 1543d at low pressure Spectrum NIR spectrum of opal-CT 1543d at low pressure

Sub-Experiment opal-CT 1548: Tamb, low T

Sub-Experiment NIR spectra of opal-CT 1548 in ambient conditions

Spectrum NIR spectrum of opal-CT 1548 under ambient conditions Spectrum NIR spectrum of opal-CT 1548 under ambient conditions

Sub-Experiment NIR spectra of opal-CT 1548 at low temperature

Spectrum NIR spectrum of opal-CT 1548 at low temperature Spectrum NIR spectrum of opal-CT 1548 at low temperature

Sub-Experiment opal-CT 1551: Tamb, low T, low P

Sub-Experiment NIR spectra of opal-CT 1551 in ambient conditions

Spectrum NIR spectrum of opal-CT 1551 under ambient conditions Spectrum NIR spectrum of opal-CT 1551 under ambient conditions

Sub-Experiment NIR spectra of opal-CT 1551 at low temperature

Spectrum NIR spectrum of opal-CT 1551 at low temperature Spectrum NIR spectrum of opal-CT 1551 at low temperature

Sub-Experiment NIR spectra of opal-CT 1551 at low pressure

Spectrum NIR spectrum of opal-CT 1551 at low pressure Spectrum NIR spectrum of opal-CT 1551 at low pressure

Sub-Experiment opal-CT 1552a: Tamb, low T, low P

Sub-Experiment NIR spectra of opal-CT 1552a in ambient conditions

Spectrum NIR spectrum of opal-CT 1552a under ambient conditions Spectrum NIR spectrum of opal-CT 1552a under ambient conditions

Sub-Experiment NIR spectra of opal-CT 1552a at low temperature

Spectrum NIR spectrum of opal-CT 1552a at low temperature Spectrum NIR spectrum of opal-CT 1552a at low temperature

Sub-Experiment NIR spectra of opal-CT 1552a at low pressure

Spectrum NIR spectrum of opal-CT 1552a at low pressure Spectrum NIR spectrum of opal-CT 1552a at low pressure

Sub-Experiment opal-CT 1552b: Tamb, low T

Sub-Experiment NIR spectra of opal-CT 1552b in ambient conditions

Spectrum NIR spectrum of opal-CT 1552b under ambient conditions Spectrum NIR spectrum of opal-CT 1552b under ambient conditions

Sub-Experiment NIR spectra of opal-CT 1552b at low temperature

Spectrum NIR spectrum of opal-CT 1552b at low temperature Spectrum NIR spectrum of opal-CT 1552b at low temperature

Sub-Experiment opal-A 1039: Tamb, low T

Sub-Experiment NIR spectra of opal-A 1039 in ambient conditions

Spectrum NIR spectrum of opal-A 1039 under ambient conditions Spectrum NIR spectrum of opal-A 1039 under ambient conditions

Sub-Experiment NIR spectra of opal-A 1039 at low pressure

Spectrum NIR spectrum of opal-A 1039 at low pressure Spectrum NIR spectrum of opal-A 1039 at low pressure

Sub-Experiment opal-CT VTB: Tamb, low P

Sub-Experiment NIR spectra of opal-CT VTB in ambient conditions

Spectrum NIR spectrum of opal-CT VTB under ambient conditions Spectrum NIR spectrum of opal-CT VTB under ambient conditions

Sub-Experiment NIR spectra of opal-CT VTB at low pressure

Spectrum NIR spectrum of opal-CT VTB at low pressure Spectrum NIR spectrum of opal-CT VTB at low pressure

Sub-Experiment opal-CT WT86: Tamb, low P

Sub-Experiment NIR spectra of opal-CT WT86 in ambient conditions

Spectrum NIR spectrum of opal-CT WT86 under ambient conditions Spectrum NIR spectrum of opal-CT WT86 under ambient conditions

Sub-Experiment NIR spectra of opal-CT WT86 at low pressure

Spectrum NIR spectrum of opal-CT WT86 at low pressure Spectrum NIR spectrum of opal-CT WT86 at low pressure

Sub-Experiment opal-CT YM12: Tamb, low P

Sub-Experiment NIR spectra of opal-CT YM12 in ambient conditions

Spectrum NIR spectrum of opal-CT YM12 under ambient conditions Spectrum NIR spectrum of opal-CT YM12 under ambient conditions

Sub-Experiment NIR spectra of opal-CT YM12 at low pressure

Spectrum NIR spectrum of opal-CT YM12 at low pressure Spectrum NIR spectrum of opal-CT YM12 at low pressure

Sub-Experiment opal-CT FT1111: Tamb, low T

Sub-Experiment NIR spectra of opal-CT FT1111 in ambient conditions

Spectrum NIR spectrum of opal-CT FT1111 under ambient conditions Spectrum NIR spectrum of opal-CT FT1111 under ambient conditions

Sub-Experiment NIR spectra of opal-CT FT1111 at low pressure

Spectrum NIR spectrum of opal-CT FT1111 at low pressure Spectrum NIR spectrum of opal-CT FT1111 at low pressure

Constituent

Name: opal
IMA name: Opal

Type

Class: silicate mineral
Compound type: tektosilicate

Constituent abundance in material

Relevance: main - major
Arrangement: single phase
Mass fraction: 1.0

Chemical composition

Formula: $SiO_2 \bullet n(H_2O)$
Chemical formula: SiO2(H2O)n
Elemental formula: Si (O)2.1-2.9 (H)0.2-1.8
Isotope mixture type: terrestrial abundance

Species

Formula	Name	Family	Number min-max	State	Relevance
$Si$	Silicon	element	1	constituent element	main
$O$	Oxygen	element	2	constituent element	main
$H_2O$	Water	molecule	0.1 - 0.9	hydration	main

Composition comments: water content may range from 3 to 21% by weight, but is usually between 6 and 10% (n = 0.2 - 0.35

Chemical functions and bonds

Chemical functions

	Function	Number	Relevance
	$R-OH$	2	main

Chemical bonds

	Bond	Number	Relevance
	$\geq Si-O-$	4
	$-O-H$	2	main

Oxides composition

Oxides

Formula	$SiO_{2}$	$H_{2}O$
Mass fraction (%)	92.0	8.0

Oxides comments

values for n=0.3, but mostly vary from 3 to 21% for H2O

Classifications

Strunz

Class: oxides - hydroxides - arsenites (04)
Division: metal:oxygen = 1:2 and similar (04.D)
Family: with small cations: Silica family (04.DA)
Code: 04.DA.10

Dana

Major class: silicates (VIII)
Class: tectosilicate Si tetrahedral frameworks (75)
Type: with H2O and organics (75.02)
Group: -Opal- group (75.02.01)
Code: 75.02.01.01

Phase

Phase type: amorphous

Crystallography

Crystal system: amorphous
Polytype: opal-AG

Physical properties

Molar mass: 61.8 - 76.2 $g/mol$
Density: 1.25 - 2.3 (av. 2.09) $g/cm^3$

Optical properties

Refringence type: isotropic
Refringence sign: no
Birefringence: 0
Refraction index $n_{\alpha}$: 1.370 - 1.470 (typ. 1.43)
Color: grayish-yellow
Diaphaneity: transparent to opaque
Luster: vitreous