Chrysocolla

Chrysocolla
Chrysocolla specimen from Ray mine, in the Scott Mountain area of Mineral Creek District, Pinal County, Arizona, US
General
CategoryPhyllosilicate minerals, mineraloids
Formula
(repeating unit)
Cu2 − xAlx(H2Si2O5)(OH)4·nH2O (x < 1)[1]
IMA symbolCcl[2]
Strunz classification9.ED.20
Crystal systemOrthorhombic
Unknown space group
Unit cella = 5.7 Å, b = 8.9 Å,
c = 6.7 Å; Z = 1
Identification
ColorBlue, cyan (blue-green), green, dark blue to black, brown, rarely yellow
Crystal habitMassive, nodular, botryoidal
Cleavagenone
FractureIrregular/uneven, sub-conchoidal
TenacityBrittle to sectile
Mohs scale hardness2.5–3.5 (7 for chrysocolla chalcedony, high-silica content)
LusterVitreous to dull
StreakWhite to a blue-green color
DiaphaneityTranslucent to opaque
Specific gravity1.9–2.4
Optical propertiesBiaxial (−)
Refractive indexnα = 1.575–1.585 nβ = 1.597 nγ = 1.598–1.635
Birefringenceδ = 0.023–0.050
References[3][4][1][5]

Chrysocolla (/ˌkrɪsəˈkɒlə/ KRIS-ə-KOL) is a hydrous copper phyllosilicate mineral and mineraloid with the formula Cu
2 – x
Al
x
(H
2
Si
2
O
5
)(OH)
4
nH
2
O
(x < 1)[1] or (Cu, Al)
2
H
2
Si
2
O
5
(OH)
4
nH
2
O)
.[4]

The structure of the mineral has been questioned, as a 2006 spectrographic study suggest material identified as chrysocolla may be a mixture of the copper hydroxide spertiniite and chalcedony.[6]

Chrysocolla typically forms amorphously.[7]

  1. ^ a b c Chrysocolla, Mindat.org
  2. ^ Warr, L. N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  3. ^ "Chrysocolla". Mineralienatlas – Fossilienatlas.
  4. ^ a b "Chrysocolla" (PDF). Handbook of Mineralogy.
  5. ^ Chrysocolla Mineral Data, WebMineral.com
  6. ^ Cite error: The named reference farges2006 was invoked but never defined (see the help page).
  7. ^ Chen, Chermaine (2021-09-02). "Chrysocolla Stone: Meaning, Uses & Other Facts about this Blue Green Crystal". The Gem Library. Retrieved 2024-07-25.