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Turquoise

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Formula:
Cu(Al,Fe3+)6(PO4)4(OH)8 · 4H2O
Colour:
bright blue, sky-blue, pale green, blue-green, turquoise-blue, apple-green, green-gray
Lustre:
Sub-Vitreous, Resinous, Waxy, Dull, Earthy
Hardness:
5 - 6
Specific Gravity:
2.6 - 2.8
Crystal System:
Triclinic
Member of:
Name:
Named from French "turques" or "turquois" meaning "Turkish" the original material found on the south slopes of the Al-Mirsah-Kuh Mountains (Iran), but which found its way to Europe via Turkey. The name was known at least as early as the 17th century C.E. Turquoise and members of its group were redefined by Foord and Taggert in 1998, with turquoise reserved for an end-member composition. Foord and Taggert (1998) also noted that most of the gem material labeled "turquoise" is inhomogeneous and that planerite is the most common constituent in commercial "turquoise".
Isostructural with:
Turquoise Group. Chalcosiderite-Turquoise Series. Planerite-Turquoise Series. The copper analogue of Faustite.

A secondary mineral occurring in the potassic alteration zone of hydrothermal porphyry copper deposits. Also formed by the action of meteoric waters, usually in arid regions, on aluminous igneous or sedimentary rocks (as vein filling in volcanic rocks and phosphatic sediments).

Visit gemdat.org for gemological information about Turquoise.


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Classification of TurquoiseHide

Approved, 'Grandfathered' (first described prior to 1959)
8.DD.15

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
D : With only medium-sized cations, (OH, etc.):RO4= 2:1
Dana 7th ed.:
42.9.3.1
42.9.3.1

42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
9 : (AB)7(XO4)4Zq·xH2O
19.2.8

19 : Phosphates
2 : Phosphates of Cu

Pronounciation of TurquoiseHide

Pronounciation:
PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Physical Properties of TurquoiseHide

Sub-Vitreous, Resinous, Waxy, Dull, Earthy
Transparency:
Transparent, Translucent, Opaque
Comment:
Dull to waxy in massive varieties, subvitreous in crystals.
Colour:
bright blue, sky-blue, pale green, blue-green, turquoise-blue, apple-green, green-gray
Comment:
Ferric iron substitution may cause the color to be green
Streak:
Pale greenish blue to white
Hardness:
5 - 6 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
on {001}, good on {010}
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
2.6 - 2.8 g/cm3 (Measured)    2.91 g/cm3 (Calculated)

Optical Data of TurquoiseHide

Type:
Biaxial (+)
RI values:
nα = 1.610 nβ = 1.615 nγ = 1.650
2V:
Measured: 40° , Calculated: 44°
Birefringence:
0.040
Max Birefringence:
δ = 0.040
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r < v strong
Pleochroism:
Weak
Comments:
X= colorless
Z= pale blue or pale green

Chemical Properties of TurquoiseHide

Formula:
Cu(Al,Fe3+)6(PO4)4(OH)8 · 4H2O
IMA Formula:
CuAl6(PO4)4(OH)8 · 4H2O
Common Impurities:
Fe,Ca

Crystallography of TurquoiseHide

Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 7.409(1) Å, b = 7.635(1) Å, c = 9.914(2) Å
α = 111.356°, β = 114.973°, γ = 69.532°
Ratio:
a:b:c = 0.97 : 1 : 1.298
Unit Cell V:
449.39 ų
Z:
1
Morphology:
Crystals rare. Steep pinacoidal crystals exhibiting {010}, {110} and {001}. Fine granular, globular crusts, veinlets, massive.

Crystallographic forms of TurquoiseHide

Crystal Atlas:
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Turquoise no.1 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

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X-Ray Powder DiffractionHide

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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
9.09 (50)
6.17 (70)
4.80 (60)
3.68 (100)
3.44 (70)
3.28 (70)
2.91 (80)
2.02 (60)
Comments:
ICDD 6-214; A very weak d(010) peak near d = 9.0 is indicative of A-site vacant material, such as planerite.

Synonyms of TurquoiseHide

Other Language Names for TurquoiseHide

Varieties of TurquoiseHide

Relationship of Turquoise to other SpeciesHide

Member of:
Other Members of this group:
Aheylite(Fe2+,Zn)Al6(PO4)4(OH)8 · 4H2OTric. 1 : P1
ChalcosideriteCuFe3+6(PO4)4(OH)8 · 4H2OTric. 1 : P1
Faustite(Zn,Cu)Al6(PO4)4(OH)8 · 4H2OTric. 1 : P1
PlaneriteAl6(PO4)2(HPO4)2(OH)8 · 4 H2OTric. 1 : P1
UM1981-32-PO:FeHFe2+Fe3+6(PO4)4-x[PO3(OH)]x(OH)8·4H2O
Forms a series with:

Common AssociatesHide

Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
ChalcedonySiO2
KaoliniteAl2(Si2O5)(OH)4
Limonite(Fe,O,OH,H2O)
Montmorillonite(Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2 · nH2O
PyriteFeS2
WavelliteAl3(PO4)2(OH,F)3 · 5H2O
Associated Minerals Based on Photo Data:
Wavellite76 photos of Turquoise associated with Wavellite on mindat.org.
Senegalite75 photos of Turquoise associated with Senegalite on mindat.org.
Quartz51 photos of Turquoise associated with Quartz on mindat.org.
Variscite24 photos of Turquoise associated with Variscite on mindat.org.
Crandallite18 photos of Turquoise associated with Crandallite on mindat.org.
Libethenite17 photos of Turquoise associated with Libethenite on mindat.org.
Varlamoffite12 photos of Turquoise associated with Varlamoffite on mindat.org.
Fluorapatite7 photos of Turquoise associated with Fluorapatite on mindat.org.
Olivenite7 photos of Turquoise associated with Olivenite on mindat.org.
Planerite7 photos of Turquoise associated with Planerite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

8.DD.05ChenevixiteCu2Fe3+2(AsO4)2(OH)4Mon. 2/m : P21/m
8.DD.05LuetheiteCu2Al2(AsO4)2(OH)4Mon. 2/m : P21/m
8.DD.10Akrochordite(Mn2+,Mg)5(AsO4)2(OH)4 · 4H2OMon. 2/m : P21/b
8.DD.10GuanacoiteCu2Mg3(AsO4)2(OH)4 · 4H2OMon. 2/m : P21/b
8.DD.15Aheylite(Fe2+,Zn)Al6(PO4)4(OH)8 · 4H2OTric. 1 : P1
8.DD.15ChalcosideriteCuFe3+6(PO4)4(OH)8 · 4H2OTric. 1 : P1
8.DD.15Faustite(Zn,Cu)Al6(PO4)4(OH)8 · 4H2OTric. 1 : P1
8.DD.15PlaneriteAl6(PO4)2(HPO4)2(OH)8 · 4 H2OTric. 1 : P1
8.DD.15AfmiteAl3(OH)4(H2O)3(PO4)(PO3OH) · H2OTric. 1 : P1
8.DD.20ChildreniteFe2+Al(PO4)(OH)2 · H2OOrth. mm2 : Ccc2
8.DD.20EosphoriteMn2+Al(PO4)(OH)2 · H2OOrth. mmm (2/m 2/m 2/m) : Cmca
8.DD.20Ernstite(Mn2+,Fe3+)Al(PO4)(OH,O)2 · H2OMon.

Related Minerals - Dana Grouping (8th Ed.)Hide

42.9.3.2CoeruleolactiteTric. 1 : P1
42.9.3.3Faustite(Zn,Cu)Al6(PO4)4(OH)8 · 4H2OTric. 1 : P1
42.9.3.4ChalcosideriteCuFe3+6(PO4)4(OH)8 · 4H2OTric. 1 : P1
42.9.3.5Aheylite(Fe2+,Zn)Al6(PO4)4(OH)8 · 4H2OTric. 1 : P1
42.9.3.6PlaneriteAl6(PO4)2(HPO4)2(OH)8 · 4 H2OTric. 1 : P1
42.9.3.6AfmiteAl3(OH)4(H2O)3(PO4)(PO3OH) · H2OTric. 1 : P1

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

19.2.1LibetheniteCu2(PO4)(OH)Orth. mmm (2/m 2/m 2/m) : Pnnm
19.2.2CornetiteCu3(PO4)(OH)3Orth. mmm (2/m 2/m 2/m) : Pbca
19.2.3ReichenbachiteCu5(PO4)2(OH)4Mon. 2/m
19.2.4LudjibaiteCu5(PO4)2(OH)4Tric. 1 : P1
19.2.5PseudomalachiteCu5(PO4)2(OH)4Mon. 2/m : P21/b
19.2.6NissoniteCu2Mg2(PO4)2(OH)2 · 5H2OMon.
19.2.7ZapataliteCu3Al4(PO4)3(OH)9 · 4H2OTet.
19.2.9SieleckiiteCu3Al4(PO4)2(OH)12 · 2H2OTric.
19.2.10PlaneriteAl6(PO4)2(HPO4)2(OH)8 · 4 H2OTric. 1 : P1
19.2.11HentscheliteCuFe3+2(PO4)2(OH)2Mon.
19.2.13ChalcosideriteCuFe3+6(PO4)4(OH)8 · 4H2OTric. 1 : P1
19.2.14Phosphofibrite(H2O,K)3.5Fe8(PO4)6(OH)7 · 5H2OMon. 2/m

Fluorescence of TurquoiseHide

Not fluorescent in UV

Other InformationHide

Notes:
Soluble with difficulty in HCl.

Often found as pseudomorphs after orthoclase; also after apatite, bone and teeth.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Jewelry stone.

References for TurquoiseHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Tavernier (1678) Voy. en Turquie, en Persie, etc., Paris.
Bocconi (1697) Museo di Fisica, etc.: 278 (as Turchine).
Fischer (1806) Mem. Soc. nat. Moscou: 1 (as Turquois orientale).
John (1806) Mem. soc. nat. Moscou: 1 (as Johnite).
John (1807) Journal für Chemie und Physik, Nuremberg: 3: 93 (as Johnite).
Onomasticon Min. Mus. Imp. Moscou (1811) (as Calaite).
Hausmann, J.F.L. (1813) Handbuch der Mineralogie 3 volumes, Göttingen: 444 (as Hydrargillite).
Blake (1883) American Journal of Science: 25: 197 (as Chalchuite).
Dana, E.S. (1892) System of Mineralogy, 6th. Edition, New York: 844.
Carnot (1894) Comptes rendus de l’Académie des sciences de Paris: 118: 995.
Penfield (1900) American Journal of Science: 10: 346.
Schaller (1912) American Journal of Science: 33: 35.
Schaller (1912) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 50: 120.
Pogue, J.E. (1915) The Turquois, a study of its history, mineralogy, geology, ethnology, archaeology, mythology, folklore, and technology. National Academy of Science Mem. 12, part 2, 207 pp.
Davy (1929) Transactions of the Royal Geology Society of Cornwall: 16: 43.
Hintze, Carl (1931) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3B]: 941.
Ball (1941) Bulletin of the Bureau of American Ethnology, Smithsonian Institution, no. 128 (Uses of turquoise in N. & S. America).
Pearl (1941) Economic Geology: 36: 335.
Northrop (1942) University of New Mexico Bulletin no. 379: 313.
Pearl (1945) Gemmologist, London: 14: 62.
Graham, R. (1947) X-ray study of chalcosiderite and turquoise. University of Toronto Studies, Geology Series, 52, 39–53.
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 646.
American Mineralogist (1953): 38: 964.
Cid-Dressner, H. (1965) Determination and refinement of the crystal structure of turquois, CuAl6(PO4)4(OH)8 •4H2O. Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 121: 87–113.
Zeitschrift für Kristallographie: 121: 87-113.
Guthrie, G.D., Jr. and D.L. Bish (1991) Refinement of the turquoise structure and determination of the hydrogen positions. Geological Society of America, Annual Meeting Abstracts with Program, 23(5), 158A (abs.).
Foord, E.E. & Taggart, J.E. (1998): A reexamination of the turquoise group; the mineral aheylite, planerite (redefined), turquoise and coeruleolactite. Mineralogical Magazine, 62, 93-111.
Extra Lapis No. 16 (1999).
Anthony, J.W., Bideaux, R.A., Bladh, K.W., and Nichols, M.C. (2000) Handbook of Mineralogy, Volume IV. Arsenates, Phosphates, Vanadates. Mineral Data Publishing, Tucson, AZ, 680pp.: 606.
Kolitsch, U. and G. Giester (2000): The crystal structure of faustite and its copper analogue turquoise. Mineral. Mag. 64, 905-913.
Y. A. Abdu, S. K. Hull, M. Fayek & F. C. Hawthorne (2011): The turquoise-chalcosiderite Cu(Al,Fe3+)6(PO4)4(OH)8•4H2O solid-solution series: A Mössbauer spectroscopy, XRD, EMPA, and FTIR study. American Mineralogist 96, 1433-1442.

Internet Links for TurquoiseHide

Localities for TurquoiseHide

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

Mineral and/or Locality  
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