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Riebeckite

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Formula:
◻[Na2][Fe32+Fe23+]Si8O22(OH)2
Riebeckite is defined as a member of the riebeckite group with Fe2+>Mg in the C2+ position and (OH) dominant in the W position.
System:
Monoclinic
Colour:
Usually black, also ...
Lustre:
Vitreous, Sub-Vitreous
Hardness:
5 - 5½
Name:
For Emil Riebeck [June 11, 1853 Preuslitz, Germany - June 22, 1885), German explorer, ethnologist, and mineralogist. Noted author and field collector of artifacts.
Isostructural with:
This page provides mineralogical data about Riebeckite.

Classification of Riebeckite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
9.DE.25

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si4O11; Clinoamphiboles
14.20.6

14 : Silicates not Containing Aluminum
20 : Silicates of Fe and alkali metals
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Type Occurrence of Riebeckite

Year of Discovery:
1888

Occurrences of Riebeckite

Geological Setting:
Syenite and undersaturated rocks

Physical Properties of Riebeckite

Vitreous, Sub-Vitreous
Diaphaneity (Transparency):
Translucent, Opaque
Colour:
Usually black, also commonly light blue to blue-black, gray-blue, gray, brown
Streak:
Pale gray to bluish-grey.
Hardness (Mohs):
5 - 5½
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {110}
Fracture:
Splintery

Crystallography of Riebeckite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Space Group Setting:
C2/m
Cell Parameters:
a = 9.76Å, b = 18.04Å, c = 5.33Å
β = 103.59°
Ratio:
a:b:c = 0.541 : 1 : 0.295
Unit Cell Volume:
V 912.18 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Prismatic {110}, frequently very elongated. May be acicular, especially in late cavities. Sometimes is very acicular in fine-grained, light colored aggregates. Well-terminated crystals are uncommon.
X-Ray Powder Diffraction Data:
d-spacingIntensity
8.40 (100)
4.51 (20)
3.42 (10)
3.27 (10)
3.12 (60)
2.80 (20)
2.73 (40)
2.18 (20)
Comments:
ICDD 19-1061

Optical Data of Riebeckite

Type:
Biaxial (-)
RI values:
nα = 1.680 - 1.698 nβ = 1.683 - 1.700 nγ = 1.685 - 1.706
2V:
Measured: 68° to 85°, Calculated: 62° to 78°
Birefringence:
0.008
Max Birefringence:
δ = 0.005 - 0.008
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
strong
Pleochroism:
Strong
Comments:
X dark blue Z blue gray to yellow green

Chemical Properties of Riebeckite

Formula:
◻[Na2][Fe32+Fe23+]Si8O22(OH)2

Riebeckite is defined as a member of the riebeckite group with Fe2+>Mg in the C2+ position and (OH) dominant in the W position.
Essential elements:
All elements listed in formula:
Common Impurities:
Fe,Ti,Mg,Al,Mn

Relationship of Riebeckite to other Species

Other Members of Group:
Fluoro-riebeckite◻{Na2}{Fe32+Fe23+}(Si8O22)F2
Magnesio-fluoro-riebeckite◻{Na2}{Mg3Fe23+}(Si8O22)F2
Magnesio-riebeckite◻{Na2}{Mg3Fe23+}(Si8O22)(OH)2
9.DE.05Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
9.DE.05Cummingtonite☐{Mg2}{Mg5}(Si8O22)(OH)2
9.DE.05Clino-holmquistite Root Name☐{Li2}{Z32+Z23+}(Si8O22)(OH,F,Cl)2
9.DE.05Grunerite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
9.DE.05Manganocummingtonite☐{Mn22+}{Mg5}(Si8O22)(OH)2
9.DE.05Manganogrunerite☐{Mn22+}{Fe52+}(Si8O22)(OH)2
9.DE.05Permanganogrunerite☐{Mn22+}{Mn52+}(Si8O22)(OH)2
9.DE.05Ferro-fluoro-pedrizite{Na}{Li2}{Fe2Al2Li}(Al2Si6O22)F2
9.DE.05Ferri-fluoro-leakeite{Na}{Na2}{Mg2Fe23+Li}(Si8O22)F2
9.DE.10Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
9.DE.10Ferri-tschermakite☐{Ca2}{Mg3Fe23+}(Al2Si6O22)(OH)2
9.DE.10Ferro-actinolite☐{Ca2}{Fe52+}(Si8O22)(OH)2
9.DE.10Ferro-hornblende☐{Ca2}{Fe42+Al}(AlSi7O22)(OH)2
9.DE.10Ferro-tschermakite☐{Ca2}{Fe32+Al2}(Al2Si6O22)(OH)2
9.DE.10Joesmithite{Pb}{Ca2}{Mg3Fe23+}(Be2Si6O22)(OH)2
9.DE.10Magnesio-hornblende☐{Ca2}{Mg4Al}(AlSi7O22)(OH)2
9.DE.10Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
9.DE.10Tschermakite☐(Ca2)(Mg3Al2)(Al2Si6O22)(OH)2
9.DE.10CannilloiteCa(Ca2)(Mg4Al)(Al3Si5O22)(OH)2
9.DE.10Fluoro-cannilloite{Ca}{Ca2}{Mg4Al}(Al3Si5O22)(F,OH)2
9.DE.10Parvo-manganotremolite☐{CaMn2+}{Mg5}(Si8O22)(OH)2
9.DE.10Fluoro-tremolite☐{Ca2}{Mg5}(Si8O22)F2
9.DE.10Potassic-fluoro-pargasite{K}{Ca2}{Mg4Al}(Al2Si6O22)F2
9.DE.15Edenite{Na}{Ca2}{Mg5}(AlSi7O22)(OH)2
9.DE.15Ferro-edenite{Na}{Ca2}{Fe52+}(AlSi7O22)(OH)2
9.DE.15Ferro-kaersutite{Na}{Ca2}{Fe32+AlTi}(Al2Si6O22)O2
9.DE.15Ferro-pargasite{Na}{Ca2}{Fe42+Al}(Al2Si6O22)(OH)2
9.DE.15Hastingsite{Na}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(OH)2
9.DE.15Kaersutite{Na}{Ca2}{Mg3AlTi}(Al2Si6O22)O2
9.DE.15Magnesio-hastingsite{Na}{Ca2}{Mg4Fe3+}(Al2Si6O22)(OH)2
9.DE.15Pargasite{Na}{Ca2}{Mg4Al}(Al2Si6O22)(OH)2
9.DE.15Sadanagaite{Na}{Ca2}{Mg3Al2}(Al3Si5O22)(OH)2
9.DE.15Fluoro-edenite{Na}{Ca2}{Mg5}(AlSi7O22)(F,OH)2
9.DE.15Potassic-ferro-ferri-sadanagaite{K}{Ca2}{Fe32+Fe23+}(Al3Si5O22)(OH)2
9.DE.15Potassic-sadanagaite{K}{Ca2}{Mg3Al2}(Al3Si5O22)(OH)2
9.DE.15Potassic-pargasite{K}{Ca2}{Mg4Al}(Al2Si6O22)(OH)2
9.DE.15Potassic-ferro-sadanagaite{K}{Ca2}{Fe32+Al2}(Al3Si5O22)(OH)2
9.DE.15Fluoro-magnesio-hastingsite{Na}{Ca2}{Mg4Fe3+}(Al2Si6O22)F2
9.DE.15Potassic-fluoro-hastingsite{K}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(F,OH)2
9.DE.15Potassic-chloro-hastingsite{K}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(Cl,OH)2
9.DE.15Fluoro-pargasite{Na}{Ca2}{Mg4Al}(Al2Si6O22)(F,OH)2
9.DE.15Parvo-mangano-edenite{Na}{CaMn2+}{Mg5}(AlSi7O22)(OH)2
9.DE.15Potassic-chloro-pargasite{K}{Ca2}{Mg4Al}(Al2Si6O22)(Cl,OH)2
9.DE.15Potassic-ferro-chloro-edenite{K}{Ca2}{Fe52+}(AlSi7O22)(Cl,OH)2
9.DE.15Potassic-magnesio-hastingsite{K}{Ca2}{Mg4Fe3+}(Al2Si6O22)(OH)2
9.DE.15Potassic-ferro-pargasite{K}{Ca2}{Fe42+Al}(Al2Si6O22)(OH)2
9.DE.15Chromio-pargasite{Na}{Ca2}{Mg4Cr3+}(Al2Si6O22)(OH)2
9.DE.20Ferro-taramiteNa(CaNa)(Fe32+Al2)(Al2Si6O22)(OH)2
9.DE.20Barroisite☐{CaNa}{Mg3Al2}(AlSi7O22)(OH)2
9.DE.20Ferro-ferri-barroisite☐(CaNa)(Fe32+Fe23+)(AlSi7O22)(OH)2
9.DE.20Ferro-ferri-winchite☐[CaNa][Fe42+(Fe3+,Al)]Si8O22(OH)2
9.DE.20Ferri-barroisite☐(CaNa)(Mg3Fe23+)(AlSi7O22)(OH)2
9.DE.20Ferro-ferri-taramiteNa(CaNa)(Fe32+Fe23+)(Al2Si6O22)(OH)2
9.DE.20Ferro-ferri-katophoriteNaCaNaFe42+(Fe3+)[(AlSi7)O22](OH)2
9.DE.20Ferro-barroisite☐{CaNa}{Fe32+Al2}(AlSi7O22)(OH)2
9.DE.20Ferro-richterite{Na}{CaNa}{Fe52+}(Si8O22)(OH)2
9.DE.20Ferro-winchite ☐{CaNa}{Fe42+Al}(Si8O22)(OH)2
9.DE.20Ferro-katophorite{Na}{CaNa}{Fe42+Al}[(AlSi7)O22](OH)2
9.DE.20Ferri-taramiteNa(CaNa)(Mg3Fe23+)(Al2Si6O22)(OH)2
9.DE.20Magnesiotaramite{Na}{CaNa}{Mg3AlFe3+}(Al2Si6O22)(OH)2
9.DE.20Richterite{Na}{CaNa}{Mg5}(Si8O22)(OH)2
9.DE.20Winchite☐{CaNa}{Mg4Al}(Si8O22)(OH)2
9.DE.20Taramite{Na}{CaNa}{Mg3Al2}(Al2Si6O22)(OH)2
9.DE.20Fluoro-richterite{Na}{CaNa}{Mg5}(Si8O22)(F,OH)2
9.DE.20Katophorite{Na}{CaNa}{Mg4Al}[(AlSi7)O22](OH)2
9.DE.20Potassic-fluoro-richterite{K}{CaNa}{Mg5}(Si8O22)(F,OH)2
9.DE.20Potassic-richteriteK[CaNa][Mg5]Si8O22(OH)2
9.DE.20Ferri-ghoseite☐[Mn2+Na][Mg4Fe3+]Si8O22(OH)2
9.DE.20Ferri-winchite☐[CaNa][Mg4(Fe3+,Al)]Si8O22(OH)2
9.DE.20Fluoro-taramite{Na}{CaNa}{Mg3Al2}(Al2Si6O22)F2
9.DE.25Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
9.DE.25EckermanniteNaNa2(Mg4Al}Si8O22(OH)2
9.DE.25Ferro-eckermanniteNaNa2(Fe2+,4Al)Si8O22(OH)2
9.DE.25Ferro-glaucophane◻[Na2][Fe32+Al2]Si8O22(OH)2
9.DE.25Glaucophane◻[Na2][Mg3Al2]Si8O22(OH)2
9.DE.25Potassic-mangani-leakeite[(Na,K)][Na2][Mg2Mn23+Li]Si8O22(OH)2
9.DE.25Mangano-ferri-eckermannite[Na][Na2][Mn42+(Fe3+)]Si8O22(OH)2
9.DE.25Ferri-leakeite[Na][Na2][Mg2Fe23+Li]Si8O22(OH)2
9.DE.25Magnesio-riebeckite◻{Na2}{Mg3Fe23+}(Si8O22)(OH)2
9.DE.25Magnesio-arfvedsonite{Na}{Na2}{Mg4Fe3+}(Si8O22)(OH)2
9.DE.25NybøiteNaNa2(Mg3Al2)(AlSi7O22)(OH)2
9.DE.25Mangano-mangani-ungarettiiteNaNa2(Mn22+Mn33+)(Si8O22)O2
9.DE.25Ferro-ferri-nybøiteNaNa2[(Fe32+,Mg)Fe23+](AlSi7O22)(OH)2
9.DE.25Clino-ferro-ferri-holmquistite◻{Li2}{Fe32+Fe23+}(Si8O22)(OH)2
9.DE.25Ferri-nybøiteNaNa2(Mg3Fe23+](AlSi7O22)(OH)2
9.DE.25Ferro-ferri-leakeite[Na][Na2][Fe22+Fe23+Li]Si8O22(OH)2
9.DE.25Ferro-ferri-fluoro-leakeiteNa(Na2)(Fe22+Fe23+Li)(Si8O22)(F)2
9.DE.25Sodic-ferri-clinoferroholmquistiteNa0.5{Li2}{Fe32+Fe23+}(Si8O22)(OH)2
9.DE.25Magnesio-fluoro-arfvedsonite[Na][Na2][Mg4Fe3+][Si8O22](F,OH)2
9.DE.25Ferri-pedrizite[Na][Li2][Mg2Fe23+Li]Si8O22(OH)2
9.DE.25Potassic-ferri-leakeite[K][Na2][Mg2Fe23+Li]Si8O22(OH)2
9.DE.25Fluoro-nybøiteNaNa2(Mg3Al2)(AlSi7O22)(F,OH)2
9.DE.25Mangani-dellaventuraite{Na}{Na2}{MgMn23+LiTi4+}Si8O22O2
9.DE.25Fluoro-pedriziteNaLi2(Mg2Al2Li)(Si8O22)F2
9.DE.25Potassic-arfvedsonite[(K,Na)][Na2][Fe42+Fe3+]Si8O22(OH)2
9.DE.25Mangani-obertiiteNa(Na2)(Mg3Mn3+Ti)(Si8O22)O2
9.DE.25Potassic-magnesio-fluoro-arfvedsonite[(K,Na)][Na2][Mg4Fe3+][Si8O22][(F,OH)2]
9.DE.25Ferro-ferri-pedrizite[Na][Li2][Fe22+Fe23+Li]Si8O22(OH)2
9.DE.25Potassic-magnesio-arfvedsonite[K][Na2][Mg4Fe3+]Si8O22(OH)2
9.DE.25PedriziteNaLi2(LiMg2Al2)(Si8O22)(OH)2
9.DE.25Ferro-pedriziteNaLi2(Fe22+Al2Li)Si8O22(OH)2
9.DE.25Fluoro-leakeiteNaNa2(Mg2Al2Li)(Si8O22)F2
9.DE.25Ferro-ferri-obertiiteNaNa2(Fe32+Fe3+Ti)Si8O22O2
14.20.1EmeleusiteLi2Na4Fe2Si12O30
14.20.2AegirineNaFe3+Si2O6
14.20.4WilkinsoniteNa2Fe42+Fe23+(Si6O18)O2
14.20.5TuperssuatsiaiteNa2Fe3Si8O20(OH)2 · 4H2O
14.20.7 Ferri-annite
14.20.8Fenaksite(K,Na)4(Fe,Mn)2(Si4O10)2(OH,F)
14.20.9Montdorite(K,Na)2(Fe2+,Mn2+,Mg)5(Si4O10)2(OH,F)4

Other Names for Riebeckite

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Riebeckite

Reference List:
Addison, C.C., Addison, W.E., Neal, G.H., and Sharp, J.H. (1962) Amphiboles. I. The oxidation of crocidolite. Journal Chem. Soc.: 1468-1471.

Hanisch, K. (1966) Messung des Ultrarot-Pleochroismus von Mineralien. VI. Der Pleochroismus des OH-Streckfrequenz in Riebeckit. Neues Jahrbuch für Mineralogie, Monatshefte 1966: 109-112.

Borg, Iris Y. (1967), Optical properties and cell parameters in the glaucophane-riebeckite series: Contributions to Mineralogy and Petrology: 15: 67-92.

Mineralogical Record: 29: 169-174.

Canadian Mineralogist (1978): 16: 187-194.

Canadian Mineralogist (1983): 21: 173.

Hawthorne, Frank C., and Roberta Oberti (2006), On the classification of amphiboles: Canadian Mineralogist:44(1): 1-21.

Frank C. Hawthorne, Roberta Oberti, George E. Harlow, Walter V. Maresch, Robert F. Martin, John C. Schumacer, Mark D. Welch (2012): Nomenclature of the amphibole supergroup, American Mineralogist, Volume 97, pages 2031–2048

Internet Links for Riebeckite

Specimens:
The following Riebeckite specimens are currently listed for sale on minfind.com.

Localities for Riebeckite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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