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Chrysocolla

This page kindly sponsored by Robert Manson North
Formula:
Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O (x < 1)
System:
Orthorhombic
Colour:
Green, bluish green, ...
Lustre:
Vitreous, Waxy, Earthy
Hardness:
2½ - 3½
Name:
The name was first used by Theophrastus in 315 B.C. and comes from the Greek chrysos, meaning "gold," and kolla, meaning "glue," in allusion to the name of the material used to solder gold. André-Jean-François-Marie Brochant de Villiers revived the name in 1808.
A mineral of secondary origin, commonly associated with other secondary copper minerals, it is typically found as glassy botryoidal or rounded masses or bubbly crusts, and as jackstraw mats of tiny acicular crystals or tufts of fibrous crystals. Copper-bearing allophane can look similar.

Visit gemdat.org for gemological information about Chrysocolla.

Classification of Chrysocolla

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Explanation of status:
The name is often used for any massive, globular, glassy, blue to green copper-bearing silicate minerals which have not been specifically identified as to species. Multiple analyses of different compositions have been offered over the years.
Chrysocolla is usually X-ray amorphous with crystallites too small to give a crystal's diffraction pattern (see Rruff pattern below). Looking at the electronic environment of Cu in chrysocolla specimens it has been found to resemble spertiniite suggesting that chrysocolla is a mixture of spertiniite and chalcedony or opal (www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-12232.pdf), which is improbable, however.
9.ED.20

9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
Dana 7th ed.:
74.3.2.1
74.3.2.1

74 : PHYLLOSILICATES Modulated Layers
3 : Modulated Layers with joined strips
14.2.5

14 : Silicates not Containing Aluminum
2 : Silicates of Cu
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Occurrences of Chrysocolla

Geological Setting:
Found in the oxidation zone of copper deposits, often encrusting or replacing earler secondary minerals.

Physical Properties of Chrysocolla

Vitreous, Waxy, Earthy
Diaphaneity (Transparency):
Translucent, Opaque
Colour:
Green, bluish green, blue, blackish blue, or brown
Streak:
Light green
Hardness (Mohs):
2½ - 3½
Hardness Data:
Measured
Tenacity:
Brittle
Cleavage:
None Observed
None
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
1.93 - 2.4 g/cm3 (Measured)    

Crystallography of Chrysocolla

Crystal System:
Orthorhombic
Cell Parameters:
a = 5.7Å, b = 8.9Å, c = 6.7Å
Ratio:
a:b:c = 0.64 : 1 : 0.753
Unit Cell Volume:
V 339.89 ų (Calculated from Unit Cell)
Morphology:
Most often found as cryptocrystalline to amorphous botryoidal aggregates and crusts. Crystals reported as fine acicular to fibrous, very rare.
Twinning:
None reported.
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
17.9 (80)
7.9 (60)
4.45 (20)
4.07 (60)
2.90 (80)
2.56 (70)
1.602 (40)
1.486 (100)
Comments:
Broad, low peaks. Weaker lines often diffuse. The pattern is fairly characteristic.

Optical Data of Chrysocolla

Type:
Biaxial (-)
RI values:
nα = 1.575 - 1.585 nβ = 1.597 nγ = 1.598 - 1.635
Max Birefringence:
δ = 0.023 - 0.050
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate

Chemical Properties of Chrysocolla

Formula:
Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O (x < 1)
Essential elements:
All elements listed in formula:

Relationship of Chrysocolla to other Species

9.ED.05DickiteAl2(Si2O5)(OH)4
9.ED.05KaoliniteAl2(Si2O5)(OH)4
9.ED.05NacriteAl2(Si2O5)(OH)4
9.ED.05Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4
9.ED.10HalloysiteAl2(Si2O5)(OH)4
9.ED.10HisingeriteFe23+(Si2O5)(OH)4 · 2H2O
9.ED.10Halloysite-7ÅAl2(Si2O5)(OH)4
9.ED.15AmesiteMg2Al(AlSiO5)(OH)4
9.ED.15AntigoriteMg3(Si2O5)(OH)4
9.ED.15Berthierine(Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4
9.ED.15Brindleyite(Ni,Al)3(Si,Al)2O5(OH)4
9.ED.15Caryopilite(Mn,Mg)3(Si2O5)(OH)4
9.ED.15ChrysotileMg3(Si2O5)(OH)4
9.ED.15CronstedtiteFe22+Fe3+((Si,Fe3+)2O5)(OH)4
9.ED.15Fraipontite(Zn,Al)3((Si,Al)2O5)(OH)4
9.ED.15GreenaliteFe2-3(Si2O5)(OH)4
9.ED.15KellyiteMn22+Al(AlSiO5)(OH)4
9.ED.15LizarditeMg3(Si2O5)(OH)4
9.ED.15ManandoniteLi2Al4(Si2AlB)O10(OH)8
9.ED.15Népouite(Ni,Mg)3(Si2O5)(OH)4
9.ED.15PecoraiteNi3(Si2O5)(OH)4
9.ED.15GuidottiiteMn2Fe3+(Fe3+SiO5)(OH)4
9.ED.20Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
9.ED.20ImogoliteAl2SiO3(OH)4
9.ED.20Neotocite(Mn,Fe,Mg)SiO3 · H2O
9.ED.25BismutoferriteFe23+Bi(SiO4)2(OH)
9.ED.25ChapmaniteFe23+Sb3+(Si2O5)O3(OH)
14.2.1DioptaseCuSiO3 · H2O
14.2.2ShattuckiteCu5(Si2O6)2(OH)2
14.2.3PlancheiteCu8(Si8O22)(OH)4 · H2O
14.2.4GilaliteCu5Si6O17 · 7H2O
14.2.6LitidioniteCuNaKSi4O10
14.2.7ReinhardbraunsiteCa5(SiO4)2(OH,F)2
14.2.8CuprorivaiteCaCu[Si4O10]
14.2.9KinoiteCa2Cu2(H2O)2[Si3O10]
14.2.10StringhamiteCaCu(SiO4) · H2O
14.2.11ApachiteCu9Si10O29 · 11H2O

Other Names for Chrysocolla

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.
Industrial Uses:
A very minor ore of copper.

References for Chrysocolla

Reference List:
François Farges, Karim Benzerara, and Gordon E. Brown, Jr., Chrysocolla Redefined as Spertiniite, SLAC-PUB-12232, Contributed to 13th International Conference On X-Ray Absorption Fine Structure (XAFS13), July 9-14, 2006, Stanford, California
( www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-12232.pdf )

Chukhrov, F.V., B.B. Zvyagin, A.I. Gorshkov, L.P. Ermilova, and E.S. Rudnitskaya (1968): Chrysocolla. Izv. Akad. Nauk SSSR, Ser. Geol., no. 6, 29{44 (in Russian).

American Mineralogist: 54: 993-994. (Abs.)

Van Oosterwyck-Gastuche, M.-C. (1970): La structure de la chrysocolle. Compt. Rendus Acad. Sci. Paris, 271, 1837-1840 (in French).

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, 8th. edition: 1561.

Sun, Ming-Shan, 1963, THE NATURE OF CHRYSOCOLLA FROM INSPIRATION MINE, ARIZONA. AMERICAN MINERALOGIST, VOL.48

Ray L. Frost and Yunfei Xi, ‎2013 Is chrysocolla (Cu,Al)2H2Si2O5(OH)4·nH2O related to spertiniite Cu(OH)2? -a vibrational spectroscopic study. http://eprints.qut.edu.au/58692/11/58692.pdf

Hariu, T., Arima, H., Sugiyama, K. (2013): The structure of hydrated copper-silicate gels, an analogue compound for natural chrysocolla. Journal of Mineralogical and Petrological Sciences 108, 111-115. [https://www.jstage.jst.go.jp/article/jmps/108/2/108_121022c/_pdf]

Internet Links for Chrysocolla

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

Localities for Chrysocolla

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.
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