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Tremolite

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Formula:
☐{Ca2}{Mg5}(Si8O22)(OH)2
The tremolite-actinolite series are defined as calcium amphiboles with A(Na+K+ 2Ca)<0,5 apfu and with C(Al+Fe3++2Ti)<0,5 apfu. The W position may contain (OH),F or Cl.

Tremolite is defined with
C2+ position: Mg>4.5 apfu
W position: (OH) dominant.

Tremolite is one of the few amphibole that has not been redefined or re-named in any of the amphibole nomenclature reports.
System:
Monoclinic
Colour:
White, brown, ...
Lustre:
Vitreous, Silky
Hardness:
5 - 6
Name:
Named in 1789 by Johann Georg Albrecht Höpfner for the Tremola Valley (Val Tremola), Central St Gotthard Massif, Tessin, Switzerland, where the type material supposedly came from, according to the dealer from whom he had acquired the specimens. However, modern investigations of what is considered the type material, conserved at Geneva, revealed that the true type locality is Campolungo, Tessin. (Val Tremola which lies north of the isograd delineating the first appearance of tremolite). This mineral was earlier (1782) called Säulenspath and Sternspath by Johann Ehrenreich von Fichtel for material from Sebeşu de Jos, Transylvania, Romania (Roth, 2006).
Tremolite forms a continuous series with the other minerals in the tremolite-actinolite series. It also forms a continuous series with edenite and richterite. At elevated PT conditions (upper amphibolite - granulite facies), the tremolite-actinolite series minerals also form a continuous series with the hornblende root name group minerals. Intermadiate compositions between cummingtonite and tremolite are also known. Tremolite is one of the few amphiboles that can be identified by EDS with reasonable certainty.

Fibrous habit.
Byssolite habit
Star and fan formed aggregates
single crystal
Pseudomorph after diopside
Fibrous habit.
Byssolite habit
Star and fan formed aggregates
single crystal
Pseudomorph after diopside
Fibrous habit.
Byssolite habit
Star and fan formed aggregates
single crystal
Pseudomorph after diopside

Tremolite is an important rock-forming mineral and occurs most commonly as a white to light green, granular to fibrous component of metamorphosed carbonate rocks, especially skarns and dolomite marbles, where the crystals and aggregates can become quite large. Any light colored amphibole in a marble will normally be tremolite. Large isolated and well-terminated crystals are rare. In this environment it commonly forms as pseudomorphs of tremolite after diopside, but can also be primary. Tremolite is also common in many metamorphosed mafic and ultramafic rocks such as amphibolites and metabasalts although actinolite and other iron-rich amphiboles usually dominate there. Fibrous (asbestiform) tremolite veins are common in many metamorphic rocktypes, especially where they are carbonate bearing. In meta-igneous rocks cummingtonite and anthophyllite can be difficult to distinguish from tremolite, but these are more restricted to metamorphosed Ca-poor ultramafic rocks like serpentinites.

dark brown tremolite
green tremolite, colored by Fe
var. hexagonite, colored by Mn
var chrome-tremolite colored by Cr and/or V
dark brown tremolite
green tremolite, colored by Fe
var. hexagonite, colored by Mn
var chrome-tremolite colored by Cr and/or V
dark brown tremolite
green tremolite, colored by Fe
var. hexagonite, colored by Mn
var chrome-tremolite colored by Cr and/or V

Although the most common color of tremolite is white or other pale colors, it may also be brown, greenish (coloured by Fe), grass green (colored by Cr and/or V) or purple (coloured by Mn).

Tremolite colored by Chrome is often called chrome-tremolite, whereas the purple variety is called hexagonite.

The amphibole varieties byssolite (hair-like fibres), and nephrite can consist, fully or partly, of tremolite.

Tremolite may be highly fibrous to asbestiform, and can then be included in the group of materials called asbestos, thought it was rarely used commercially. As with all asbestiform minerals, this fibrous variety is considered carcinogenic if ground into fine dust and inhaled in large amounts, so people should use care in its handling.

For further information, see the tremolite best mineral article, see link: http://www.mindat.org/mesg-86-198178.html

Visit gemdat.org for gemological information about Tremolite.

Classification of Tremolite

Approved, 'Grandfathered' (first described prior to 1959)
9.DE.10

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si4O11; Clinoamphiboles
66.1.3a.1

66 : INOSILICATES Double-Width,Unbranched Chains,(W=2)
1 : Amphiboles - Mg-Fe-Mn-Li subgroup
14.6.13

14 : Silicates not Containing Aluminum
6 : Silicates of Ca with alkali or Mg or both
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Type Occurrence of Tremolite

Geological Setting of Type Material:
Dolomite marble

Occurrences of Tremolite

Geological Setting:
A common rock-forming mineral in contact metamorphosed Ca+/-Mg siliceous carbonate sediments, regional greenschist to amphibolite-facies metamorphosed mafic and ultramafic rocks and dolomitic rocks, many skarns and veins, and some metamorphic ore deposits. See Deer et al., 1997.

Physical Properties of Tremolite

Vitreous, Silky
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
White, brown, colourless, grey, light green, green, light yellow, pink-violet
Streak:
White
Hardness (Mohs):
5 - 6
Tenacity:
Brittle
Cleavage:
Perfect
on {110}
Parting:
on {010} {100}
Fracture:
Splintery
Density:
2.99 - 3.03 g/cm3 (Measured)    2.964 g/cm3 (Calculated)

Crystallography of Tremolite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Cell Parameters:
a = 9.84Å, b = 18.02Å, c = 5.27Å
β = 104.95°
Ratio:
a:b:c = 0.546 : 1 : 0.292
Unit Cell Volume:
V 902.83 ų (Calculated from Unit Cell)
Morphology:
Elongated, stout prismatic, bladed, fibrous, granular, columnar crystals and aggregates.

Twinning:
Simple or multiple: common parallel to {100}, rarely parallel to {001}
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction Data:
d-spacingIntensity
3.12 (100)
8.38 (100)
2.71 (90)

Optical Data of Tremolite

Type:
Biaxial (-)
RI values:
nα = 1.599 - 1.612 nβ = 1.613 - 1.626 nγ = 1.625 - 1.637
2V:
Measured: 88° to 80°, Calculated: 82° to 84°
Max Birefringence:
δ = 0.026
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r < v weak

Chemical Properties of Tremolite

Formula:
☐{Ca2}{Mg5}(Si8O22)(OH)2

The tremolite-actinolite series are defined as calcium amphiboles with A(Na+K+ 2Ca)<0,5 apfu and with C(Al+Fe3++2Ti)<0,5 apfu. The W position may contain (OH),F or Cl.

Tremolite is defined with
C2+ position: Mg>4.5 apfu
W position: (OH) dominant.

Tremolite is one of the few amphibole that has not been redefined or re-named in any of the amphibole nomenclature reports.
All elements listed in formula:
Common Impurities:
Ti,Mn,Al,Na,K,F,Cl,H2O

Relationship of Tremolite to other Species

Series:
Forms a series with Actinolite (see here)
Forms a series with Ferro-actinolite (see here)
Other Members of Group:
Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Ferro-actinolite☐{Ca2}{Fe52+}(Si8O22)(OH)2
Ferro-fluoro-actinolite☐{Ca2}{Fe5}(Si8O22)F2
Fluoro-tremolite☐{Ca2}{Mg5}(Si8O22)F2
Common Associates:
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.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}(Si5Al3O22)(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.15Magnesio-fluoro-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-katophoriteNa(NaCa)(Fe42+Fe3+)(Si7Al)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}{NaCa}{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(Fe42+Al)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.25Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(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
14.6.1CombeiteNa2Ca2(Si6O18)0.5
14.6.2PectoliteNaCa2Si3O8(OH)
14.6.3Pectolite-M2abcNaCa2[HSi3O9]
14.6.4DenisoviteCa2(K,Na)Si3O8(F,OH)2
14.6.5TokkoiteK2Ca4[Si7O18(OH)](OH,F)
14.6.6MountainiteKNa2Ca2[Si8O19(OH)] · 6H2O
14.6.7RhodesiteKHCa2Si8O19 · 5H2O
14.6.8MiseriteK1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2O
14.6.9ÅkermaniteCa2Mg(Si2O7)
14.6.10MonticelliteCaMgSiO4
14.6.11MerwiniteCa3Mg(SiO4)2
14.6.12DiopsideCaMgSi2O6

Other Names for Tremolite

Other Information

Health Risks:
Asbestiform varieties of tremolite can cause lung disease when inhaled, as with other species of asbestos minerals.

References for Tremolite

Reference List:
Höpfner, J.G.A. (1789) I. “Ueber die Klassifikation der Fossilien in einem Schreiben des Herausgebers an Herrn Dr. Karsten in Halle. II. “Versuch einer neuen Classifikationsmethode der Stein- und Erdarten, nach den neuesten chemischen Erfahrungen". Magazin für die Naturkunde Helvetiens: 4: 255-332.

Ross, M., Smith, W.L., Ashton, W.H. (1968) Triclinic talc and associated amphiboles from Gouverneur mining district, New York. American Mineralogist 53: 763-765.

Hawthorne, F.C., Grundy, H.D. (1976) The crystal chemistry of the amphiboles; IV, X-ray and neutron refinements of the crystal structure of tremolite. The Canadian Mineralogist: 14: 334-345.

Hawthorne, F.C., Della Ventura, G., Robert, J.-L. (1996) Short-range order of (Na,K) and Al in tremolite: An infrared study. American Mineralogist: 81: 782-784.

Deer, W.A., Howie, R.A., J. Zussman. (1997) Rock-forming Minerals: Double-Chain Silicates, Volume 2B;. Geological Society of London.

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.

Ishida, K. Hawthorne, F.C., Ando, Y. (2002) Fine structure of infrared OH-stretching bands in natural and heat-treated amphiboles of the tremolite-ferroactinolite series. American Mineralogist: 87: 891-898.

Roth, P. (2006) The early history of tremolite. Axis: 2(3): 1-10.
Roth, P. (2006) http://www.minrec.org/pdfs/TREMOLITE%20Edited.pdf

Hawthorne, F.C., Oberti, R. (2006) On the classification of amphiboles. The Canadian Mineralogist: 44(1): 1-21.


Internet Links for Tremolite

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

Localities for Tremolite

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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