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Actinolite

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Formula:
☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Colour:
Green, green-black, grey-green, or black
Lustre:
Vitreous, Silky
Hardness:
5 - 6
Specific Gravity:
3.03 - 3.24
Crystal System:
Monoclinic
Name:
Named in 1794 by Richard Kirwan from the Greek ακτίνα ("aktina") for "ray" and λίθος ("lithos") for "stone" in allusion to the fibrous nature of the original specimens.
Type locality not known.
Note: Tremolite is defined as having an Mg/(Mg+Fe2+) ratio ≥ 0.9; actinolite has a ratio of 0.5–0.9 and ferro-actinolite has a ratio of less than 0.5. The name actinolite was retained in the nomenclature, since it is entrenched in the literature.

As bladed crystals, to 15 cm; columnar, may be kinked or bent; radiating fibrous to asbestiform; granular to massive.

Visit gemdat.org for gemological information about Actinolite.


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Classification of ActinoliteHide

Approved, 'Grandfathered' (first described prior to 1959)
Notes:
Redefined by the IMA
First Published:
1794
Approval History:
Redefined by IMA in 2012 (special procedure).
9.DE.10

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si4O11; Clinoamphiboles
14.23.2

14 : Silicates not Containing Aluminum
23 : Silicates of Fe, Mg, Ca

Pronounciation of ActinoliteHide

Pronounciation:
PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Physical Properties of ActinoliteHide

Vitreous, Silky
Transparency:
Transparent, Translucent
Colour:
Green, green-black, grey-green, or black
Comment:
Colourless, pale green to deep green in thin section.
Streak:
White
Hardness:
5 - 6 on Mohs scale
Hardness Data:
Measured
Tenacity:
Brittle
Cleavage:
Distinct/Good
on {110}
Parting:
on {100}
Fracture:
Splintery
Density:
3.03 - 3.24 g/cm3 (Measured)    3.07 g/cm3 (Calculated)

Optical Data of ActinoliteHide

Type:
Biaxial (-)
RI values:
nα = 1.613 - 1.646 nβ = 1.624 - 1.656 nγ = 1.636 - 1.666
2V:
Measured: 79° to 86°, Calculated: 78° to 82°
Max Birefringence:
δ = 0.023
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r < v
Pleochroism:
Weak
Comments:
X= pale yellow, yellowish green
Y= pale yellow-gree, green
Z= pale green, deep greenish blue

Chemical Properties of ActinoliteHide

Formula:
☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
IMA Formula:
Ca2(Mg4.5-2.5Fe2+0.5-2.5)Σ=5Si8O22(OH)2
Idealised Formula:
☐{Ca2}{(Mg,Fe2+)5}(Si8O22)(OH)2
Common Impurities:
Mn,Al,Na,K,Ti

Age informationHide

Age range:
Orosirian : 1943 Ma to 1835 Ma - based on data given below.
Sample ages:
Sample IDRecorded ageGeologic TimeDating method
11853 to 1835 MaOrosirianAr-Ar
21895 to 1877 MaOrosirianAr-Ar
31915 to 1897 MaOrosirianAr-Ar
41943 to 1927 MaOrosirianAr-Ar
Sample references:
IDLocalityReference
1Beaver Mine, Coleman Township, Cobalt area, Cobalt-Gowganda region, Timiskaming District, Ontario, CanadaAndrews, A. J., Masliwec, A., Morris, W. A., Owsiacki, L., & York, D. (1986) The silver deposits at Cobalt and Gowganda, Ontario. II: An experiment in age determinations employing radiometric and paleomagnetic measurements.Canadian Journal of Earth Sciences, 23(10), 1507-1518.
2  "  "  "  "
3  "  "  "  "
4  "  "  "  "

Crystallography of ActinoliteHide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 9.891 Å, b = 18.2 Å, c = 5.31 Å
β = 104.64°
Ratio:
a:b:c = 0.543 : 1 : 0.292
Unit Cell V:
924.85 ų (Calculated from Unit Cell)
Z:
2
Twinning:
simple or lamellar, common parallel {100}; lamellar, less common parallel {001}

X-Ray Powder DiffractionHide

Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
8.47 (70)
5.305 (10)
4.91 (70)
3.401 (80)
3.143 (70)
2.719 (100)
2.543 (100)
Comments:
ICDD 25-0157

Synonyms of ActinoliteHide

Other Language Names for ActinoliteHide

Varieties of ActinoliteHide

SmaragditeAn emerald green variety of actinolite, owing its colour to a faint chromium content.

Relationship of Actinolite to other SpeciesHide

Other Members of this group:
Ferro-actinolite☐{Ca2}{Fe2+5}(Si8O22)(OH)2Mon.
Ferro-fluoro-actinolite☐{Ca2}{Fe5}(Si8O22)F2
Fluoro-tremolite☐{Ca2}{Mg5}(Si8O22)F2Mon. 2/m : B2/m
Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2Mon. 2/m : B2/m
Forms a series with:

Common AssociatesHide

AlbiteNa(AlSi3O8)
Chlorite GroupA group of mostly monoclinic (also triclinic or orthorhombic) micaceous phyllosilicate minerals with a structure ...
Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Glaucophane◻[Na2][Mg3Al2]Si8O22(OH)2
LawsoniteCaAl2(Si2O7)(OH)2 · H2O
PumpellyiteSynonymous with members of the Pumpellyite Group (which includes also 'julgoldite').
TalcMg3Si4O10(OH)2
Associated Minerals Based on Photo Data:
Quartz164 photos of Actinolite associated with Quartz on mindat.org.
Calcite132 photos of Actinolite associated with Calcite on mindat.org.
Epidote96 photos of Actinolite associated with Epidote on mindat.org.
Titanite46 photos of Actinolite associated with Titanite on mindat.org.
Magnetite38 photos of Actinolite associated with Magnetite on mindat.org.
Talc38 photos of Actinolite associated with Talc on mindat.org.
Oligoclase38 photos of Actinolite associated with Oligoclase on mindat.org.
Axinite-(Fe)37 photos of Actinolite associated with Axinite-(Fe) on mindat.org.
Prehnite37 photos of Actinolite associated with Prehnite on mindat.org.
Dyscrasite36 photos of Actinolite associated with Dyscrasite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.DE.05Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2Orth. mmm (2/m 2/m 2/m) : Pnma
9.DE.05Cummingtonite☐{Mg2}{Mg5}(Si8O22)(OH)2Mon.
9.DE.05Clino-holmquistite Root Name☐{Li2}{Z2+3Z3+2}(Si8O22)(OH,F,Cl)2Mon.
9.DE.05Grunerite☐{Fe2+2}{Fe2+5}(Si8O22)(OH)2Mon. 2/m : B2/m
9.DE.05Manganocummingtonite☐{Mn2+2}{Mg5}(Si8O22)(OH)2Mon. 2/m : B2/m
9.DE.05Manganogrunerite☐{Mn2+2}{Fe2+5}(Si8O22)(OH)2Mon.
9.DE.05Permanganogrunerite☐{Mn2+2}{Mn2+5}(Si8O22)(OH)2Mon.
9.DE.05Ferro-fluoro-pedrizite{Na}{Li2}{Fe2Al2Li}(Al2Si6O22)F2Mon. 2/m : B2/m
9.DE.05Ferri-fluoro-leakeite{Na}{Na2}{Mg2Fe3+2Li}(Si8O22)F2Mon. 2/m : B2/m
9.DE.10Ferri-tschermakite☐{Ca2}{Mg3Fe3+2}(Al2Si6O22)(OH)2Mon.
9.DE.10Ferro-actinolite☐{Ca2}{Fe2+5}(Si8O22)(OH)2Mon.
9.DE.10Ferro-hornblende☐{Ca2}{Fe2+4Al}(AlSi7O22)(OH)2Mon.
9.DE.10Ferro-tschermakite☐{Ca2}{Fe2+3Al2}(Al2Si6O22)(OH)2Mon. 2/m : B2/m
9.DE.10Joesmithite{Pb}{Ca2}{Mg3Fe3+2}(Be2Si6O22)(OH)2Mon.
9.DE.10Magnesio-hornblende☐{Ca2}{Mg4Al}(AlSi7O22)(OH)2Mon.
9.DE.10Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2Mon. 2/m : B2/m
9.DE.10Tschermakite☐(Ca2)(Mg3Al2)(Al2Si6O22)(OH)2Mon. 2/m : B2/m
9.DE.10CannilloiteCa(Ca2)(Mg4Al)(Al3Si5O22)(OH)2Mon.
9.DE.10Fluoro-cannilloite{Ca}{Ca2}{Mg4Al}(Al3Si5O22)(F,OH)2Mon.
9.DE.10Parvo-manganotremolite☐{CaMn2+}{Mg5}(Si8O22)(OH)2Mon. 2/m : B2/m
9.DE.10Fluoro-tremolite☐{Ca2}{Mg5}(Si8O22)F2Mon. 2/m : B2/m
9.DE.10Potassic-fluoro-pargasite{K}{Ca2}{Mg4Al}(Al2Si6O22)F2Mon. 2/m : B2/m
9.DE.15Edenite{Na}{Ca2}{Mg5}(AlSi7O22)(OH)2Mon.
9.DE.15Ferro-edenite{Na}{Ca2}{Fe2+5}(AlSi7O22)(OH)2Mon.
9.DE.15Ferro-kaersutite{Na}{Ca2}{Fe2+3AlTi}(Al2Si6O22)O2Mon.
9.DE.15Ferro-pargasite{Na}{Ca2}{Fe2+4Al}(Al2Si6O22)(OH)2Mon.
9.DE.15Hastingsite{Na}{Ca2}{Fe2+4Fe3+}(Al2Si6O22)(OH)2Mon.
9.DE.15Kaersutite{Na}{Ca2}{Mg3AlTi}(Al2Si6O22)O2 Mon.
9.DE.15Magnesio-hastingsite{Na}{Ca2}{Mg4Fe3+}(Al2Si6O22)(OH)2Mon.
9.DE.15Pargasite{Na}{Ca2}{Mg4Al}(Al2Si6O22)(OH)2Mon.
9.DE.15Sadanagaite{Na}{Ca2}{Mg3Al2}(Si5Al3O22)(OH)2Mon.
9.DE.15Fluoro-edenite{Na}{Ca2}{Mg5}(AlSi7O22)(F,OH)2Mon. 2/m : P2/m
9.DE.15Potassic-ferro-ferri-sadanagaite{K}{Ca2}{Fe2+3Fe3+2}(Al3Si5O22)(OH)2Mon.
9.DE.15Potassic-sadanagaite{K}{Ca2}{Mg3Al2}(Al3Si5O22)(OH)2Mon.
9.DE.15Potassic-pargasite{K}{Ca2}{Mg4Al}(Al2Si6O22)(OH)2Mon.
9.DE.15Potassic-ferro-sadanagaite{K}{Ca2}{Fe2+3Al2}(Al3Si5O22)(OH)2Mon.
9.DE.15Magnesio-fluoro-hastingsite{Na}{Ca2}{Mg4Fe3+}(Al2Si6O22)F2Mon. 2/m : B2/m
9.DE.15Potassic-fluoro-hastingsite{K}{Ca2}{Fe2+4Fe3+}(Al2Si6O22)(F,OH)2Mon. 2/m : B2/m
9.DE.15Potassic-chloro-hastingsite{K}{Ca2}{Fe2+4Fe3+}(Al2Si6O22)(Cl,OH)2Mon. 2/m : B2/m
9.DE.15Fluoro-pargasite{Na}{Ca2}{Mg4Al}(Al2Si6O22)(F,OH)2Mon. 2/m : B2/m
9.DE.15Parvo-mangano-edenite{Na}{CaMn2+}{Mg5}(AlSi7O22)(OH)2Mon. 2/m : B2/m
9.DE.15Potassic-chloro-pargasite{K}{Ca2}{Mg4Al}(Al2Si6O22)(Cl,OH)2
9.DE.15Potassic-ferro-chloro-edenite{K}{Ca2}{Fe2+5}(AlSi7O22)(Cl,OH)2
9.DE.15Potassic-magnesio-hastingsite{K}{Ca2}{Mg4Fe3+}(Al2Si6O22)(OH)2Mon. 2/m : B2/m
9.DE.15Potassic-ferro-pargasite{K}{Ca2}{Fe2+4Al}(Al2Si6O22)(OH)2Mon. 2/m : B2/m
9.DE.15Chromio-pargasite{Na}{Ca2}{Mg4Cr3+}(Al2Si6O22)(OH)2Mon. 2/m : B2/m
9.DE.20Ferro-taramiteNa(CaNa)(Fe2+3Al2)(Al2Si6O22)(OH)2Mon. 2/m : B2/m
9.DE.20Barroisite☐{CaNa}{Mg3Al2}(AlSi7O22)(OH)2Mon.
9.DE.20Ferro-ferri-barroisite☐(CaNa)(Fe2+3Fe3+2)(AlSi7O22)(OH)2
9.DE.20Ferro-ferri-winchite☐[CaNa][Fe2+4(Fe3+,Al)]Si8O22(OH)2
9.DE.20Ferri-barroisite☐(CaNa)(Mg3Fe3+2)(AlSi7O22)(OH)2
9.DE.20Ferro-ferri-taramiteNa(CaNa)(Fe2+3Fe3+2)(Al2Si6O22)(OH)2
9.DE.20Ferro-ferri-katophoriteNa(NaCa)(Fe2+4Fe3+)(Si7Al)O22(OH)2Mon. 2/m : B2/m
9.DE.20Ferro-barroisite☐{CaNa}{Fe2+3Al2}(AlSi7O22)(OH)2Mon. 2/m : B2/m
9.DE.20Ferro-richterite{Na}{CaNa}{Fe2+5}(Si8O22)(OH)2Mon.
9.DE.20Ferro-winchite ☐{CaNa}{Fe2+4Al}(Si8O22)(OH)2Mon.
9.DE.20Ferro-katophorite{Na}{CaNa}{Fe2+4Al}[(AlSi7)O22](OH)2
9.DE.20Ferri-taramiteNa(CaNa)(Mg3Fe3+2)(Al2Si6O22)(OH)2Mon.
9.DE.20Magnesiotaramite{Na}{CaNa}{Mg3AlFe3+}(Al2Si6O22)(OH)2Mon.
9.DE.20Richterite{Na}{NaCa}{Mg5}(Si8O22)(OH)2Mon.
9.DE.20Winchite☐{CaNa}{Mg4Al}(Si8O22)(OH)2Mon.
9.DE.20Taramite{Na}{CaNa}{Mg3Al2}(Al2Si6O22)(OH)2Mon. 2/m : B2/m
9.DE.20Fluoro-richterite{Na}{CaNa}{Mg5}(Si8O22)(F,OH)2Mon. 2/m
9.DE.20Katophorite{Na}{CaNa}{Mg4Al}[(AlSi7)O22](OH)2Mon. 2/m : B2/m
9.DE.20Potassic-fluoro-richterite{K}{CaNa}{Mg5}(Si8O22)(F,OH)2Mon.
9.DE.20Potassic-richteriteK[CaNa][Mg5]Si8O22(OH)2Mon.
9.DE.20Ferri-ghoseite☐[Mn2+Na][Mg4Fe3+]Si8O22(OH)2Mon. 2/m
9.DE.20Ferri-winchite☐[CaNa][Mg4(Fe3+,Al)]Si8O22(OH)2Mon. 2/m : B2/m
9.DE.20Fluoro-taramite{Na}{CaNa}{Mg3Al2}(Al2Si6O22)F2Mon. 2/m : B2/m
9.DE.25Arfvedsonite[Na][Na2][Fe2+4Fe3+]Si8O22(OH)2Mon. 2/m : B2/m
9.DE.25EckermanniteNaNa2(Mg4Al}Si8O22(OH)2Mon. 2/m : B2/m
9.DE.25Ferro-eckermanniteNaNa2(Fe2+4Al)Si8O22(OH)2Mon.
9.DE.25Ferro-glaucophane◻[Na2][Fe2+3Al2]Si8O22(OH)2Mon.
9.DE.25Glaucophane◻[Na2][Mg3Al2]Si8O22(OH)2Mon.
9.DE.25Potassic-mangani-leakeite[(Na,K)][Na2][Mg2Mn3+2Li]Si8O22(OH)2Mon.
9.DE.25Mangano-ferri-eckermannite[Na][Na2][Mn2+4(Fe3+)]Si8O22(OH)2Mon.
9.DE.25Ferri-leakeite[Na][Na2][Mg2Fe3+2Li]Si8O22(OH)2Mon.
9.DE.25Magnesio-riebeckite◻{Na2}{Mg3Fe3+2}(Si8O22)(OH)2Mon.
9.DE.25Magnesio-arfvedsonite{Na}{Na2}{Mg4Fe3+}(Si8O22)(OH)2Mon. 2/m : B2/m
9.DE.25NybøiteNaNa2(Mg3Al2)(AlSi7O22)(OH)2Mon.
9.DE.25Riebeckite◻[Na2][Fe2+3Fe3+2]Si8O22(OH)2Mon. 2/m : B2/m
9.DE.25Mangano-mangani-ungarettiiteNaNa2(Mn2+2Mn3+3)(Si8O22)O2Mon.
9.DE.25Ferro-ferri-nybøiteNaNa2[(Fe2+3,Mg)Fe3+2](AlSi7O22)(OH)2Mon. 2/m : B2/m
9.DE.25Clino-ferro-ferri-holmquistite◻{Li2}{Fe2+3Fe3+2}(Si8O22)(OH)2Mon. 2/m : B2/m
9.DE.25Ferri-nybøiteNaNa2(Mg3Fe3+2](AlSi7O22)(OH)2Mon.
9.DE.25Ferro-ferri-leakeite[Na][Na2][Fe2+2Fe3+2Li]Si8O22(OH)2Mon.
9.DE.25Ferro-ferri-fluoro-leakeiteNa(Na2)(Fe2+2Fe3+2Li)(Si8O22)(F)2Mon.
9.DE.25Sodic-ferri-clinoferroholmquistiteNa0.5{Li2}{Fe2+3Fe3+2}(Si8O22)(OH)2Mon.
9.DE.25Magnesio-fluoro-arfvedsonite[Na][Na2][Mg4Fe3+][Si8O22](F,OH)2Mon.
9.DE.25Ferri-pedrizite[Na][Li2][Mg2Fe3+2Li]Si8O22(OH)2Mon.
9.DE.25Potassic-ferri-leakeite[K][Na2][Mg2Fe3+2Li]Si8O22(OH)2Mon. 2/m : B2/m
9.DE.25Fluoro-nybøiteNaNa2(Mg3Al2)(AlSi7O22)(F,OH)2Mon. 2/m : B2/m
9.DE.25Mangani-dellaventuraite{Na}{Na2}{MgMn3+2LiTi4+}Si8O22O2Mon. 2/m : B2/m
9.DE.25Fluoro-pedriziteNaLi2(Mg2Al2Li)(Si8O22)F2Mon. 2/m : B2/m
9.DE.25Potassic-arfvedsonite[(K,Na)][Na2][Fe2+4Fe3+]Si8O22(OH)2Mon. 2/m : B2/m
9.DE.25Mangani-obertiiteNa(Na2)(Mg3Mn3+Ti)(Si8O22)O2Mon. 2/m : B2/m
9.DE.25Potassic-magnesio-fluoro-arfvedsonite[(K,Na)][Na2][Mg4Fe3+][Si8O22][(F,OH)2]
9.DE.25Ferro-ferri-pedrizite[Na][Li2][Fe2+2Fe3+2Li]Si8O22(OH)2Mon. 2/m : B2/m
9.DE.25Potassic-magnesio-arfvedsonite[K][Na2][Mg4Fe3+]Si8O22(OH)2Mon. 2/m : B2/m
9.DE.25PedriziteNaLi2(LiMg2Al2)(Si8O22)(OH)2Mon. 2/m : B2/m
9.DE.25Ferro-pedriziteNaLi2(Fe2+2Al2Li)Si8O22(OH)2Mon. 2/m : B2/m
9.DE.25Fluoro-leakeiteNaNa2(Mg2Al2Li)(Si8O22)F2Mon. 2/m : B2/m
9.DE.25Ferro-ferri-obertiiteNaNa2(Fe2+3Fe3+Ti)Si8O22O2Mon. 2/m : B2/m

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.23.1Pigeonite(CaxMgyFez)(Mgy1Fez1)Si2O6Mon. 2/m : P21/b

Other InformationHide

Health Risks:
Dust from asbestiform varieties of actinolite can cause serious and irreversible lung disease when inhaled. Avoid creating or inhaling dust.

Actinolite in petrologyHide

References for ActinoliteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Kirwan, R. (1794) 16th species: actynolite. in Elements of Mineralogy, 2nd Edition, Volume 1, Elmsly (London) 167-170.
Hawthorne, F.C. (1983) The crystal chemistry of the amphiboles; Introduction. The Canadian Mineralogist: 21: 174.
Hawthorne, F.C. (1983) The crystal chemistry of the amphiboles; Classification and nomenclature. The Canadian Mineralogist: 21: 175-176.
Mandarino, J.A. (1998) The Second List of Additions and Corrections to the Glossary of Mineral Species (1995). The Amphibole Group. Mineralogical Record: 29: 169-174.
Hawthorne, F.C., Oberti, R. (2006) On the classification of amphiboles. The Canadian Mineralogist: 44: 1-21.

Internet Links for ActinoliteHide

Localities for ActinoliteHide

This 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.

Locality ListShow