Gilalite
A valid IMA mineral species
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About Gilalite
Seal of Gila County, AZ
Formula:
Cu5Si6O17 · 7H2O
Colour:
Translucent green, blue-green
Hardness:
2
Specific Gravity:
2.72
Crystal System:
Monoclinic
Name:
For Gila Co., Arizona, USA, where it was found. It is pronounced hee'-lah-lite.
This page provides mineralogical data about Gilalite.
Unique Identifiers
Mindat ID:
1691
Long-form identifier:
mindat:1:1:1691:5
Similar Names
| Lilalite | A synonym of Lepidolite |
IMA Classification of Gilalite
Approved
IMA Formula:
Cu2+5Si6O17·7H2O
Approval year:
1979
First published:
1980
Classification of Gilalite
9.HE.05
9 : SILICATES (Germanates)
H : Unclassified silicates
E : With Cu, Zn
9 : SILICATES (Germanates)
H : Unclassified silicates
E : With Cu, Zn
78.4.4.1
78 : Unclassified Silicates
4 :
78 : Unclassified Silicates
4 :
14.2.4
14 : Silicates not Containing Aluminum
2 : Silicates of Cu
14 : Silicates not Containing Aluminum
2 : Silicates of Cu
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Gil | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Gilalite
Transparency:
Transparent, Translucent
Comment:
Nonmetallic
Colour:
Translucent green, blue-green
Hardness:
2 on Mohs scale
Tenacity:
Waxy
Density:
2.72(5) g/cm3 (Measured) 2.54 g/cm3 (Calculated)
Optical Data of Gilalite
Type:
Biaxial (-)
RI values:
nα = 1.56 nβ = 1.635 nγ = 1.635
Max. Birefringence:
δ = 0.075
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (-0°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (-0°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
none
Optical Extinction:
Blades extinguish up to 8° from Z || length.
Pleochroism:
Weak
Comments:
Weak in drab grayish green.
Comments:
2Vmeasured = Very small.
Absorption: Z > X = Y.
Absorption: Z > X = Y.
Chemistry of Gilalite
Mindat Formula:
Cu5Si6O17 · 7H2O
Element Weights:
Elements listed:
Common Impurities:
Mn,Mg,Ca
Crystallography of Gilalite
Crystal System:
Monoclinic
Cell Parameters:
a = 13.38 Å, b = 19.16 Å, c = 9.02 Å
β = 90°
β = 90°
Ratio:
a:b:c = 0.698 : 1 : 0.471
Unit Cell V:
2,312.37 ų (Calculated from Unit Cell)
Z:
4
Comment:
Neither point group nor space group known.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 13.4 Å | (100) |
| 7.786 Å | (50) |
| 4.790 Å | (40) |
| 3.897 Å | (40) |
| 10.97 Å | (30) |
| 6.684 Å | (30) |
| 3.315 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 12 : Hadean hydrothermal subsurface sulfide deposits (see also #33) | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 56 : Slag and smelter minerals (see also #51 and #55) |
Type Occurrence of Gilalite
General Appearance of Type Material:
Spherules of radial fibers up to 0.2 mm or more in length.
Place of Conservation of Type Material:
The Natural History Museum, London, England, 1980,533; University of Arizona, Tucson, Arizona; National Museum of Natural History, Washington, D.C., USA, 150201.
Geological Setting of Type Material:
Retrograde or mesogene mineral occurring in tactites.
Associated Minerals at Type Locality:
Synonyms of Gilalite
Other Language Names for Gilalite
Common Associates
Associations Based on Photo Data:
| 61 photos of Gilalite associated with Kinoite | Ca2Cu2(H2O)2[Si3O10] |
| 23 photos of Gilalite associated with Apophyllite Group | AB4[Si8O20]X · 8H2O |
| 16 photos of Gilalite associated with Ruizite | Ca2Mn3+2[Si4O11(OH)2](OH)2 · 2H2O |
| 12 photos of Gilalite associated with Quartz | SiO2 |
| 9 photos of Gilalite associated with Fluorapophyllite-(K) | KCa4(Si8O20)(F,OH) · 8H2O |
| 9 photos of Gilalite associated with Apachite | Cu9Si10O29 · 11H2O |
| 9 photos of Gilalite associated with Hydroxyapophyllite-(K) | KCa4(Si8O20)(OH,F) · 8H2O |
| 3 photos of Gilalite associated with Cuprite | Cu2O |
| 2 photos of Gilalite associated with Brochantite | Cu4(SO4)(OH)6 |
| 2 photos of Gilalite associated with Junitoite | CaZn2Si2O7 · H2O |
Related Minerals - Strunz-mindat Grouping
| 9.HE.10 | Apachite | Cu9Si10O29 · 11H2O |
Other Information
Notes:
Easily soluble in cold, dilute HNO3 or HCl.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Gilalite
mindat.org URL:
https://www.mindat.org/min-1691.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Gilalite
Reference List:
Cesbron, F. P., Williams, S. A. (1980) Apachite and gilalite, two new copper silicates from Christmas, Arizona. Mineralogical Magazine, 43 (329) 639-641 doi:10.1180/minmag.1980.043.329.12
Fleischer, M., Cabri, L. J., Chao, G. Y., Pabst, A. (1980) New mineral names. American Mineralogist, 65 (9-10). 1065-1070
Localities for Gilalite
Showing 8 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Brazil | |
| Lavinsky (n.d.) | |
| Gems & Gemology Magazine Fall 2005 ... |
Greece | |
| 58. +1 other reference |
Italy | |
| Vergani et al. (2020) |
| Vergani et al. (2020) |
USA (TL) | |
| Cesbron et al. (1980) +1 other reference |
| Eckhard D. Stuart | |
| Castor et al. (2004) |
Quick NavTopAbout GilaliteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Christmas Mine, Christmas, Banner Mining District, Gila County, Arizona, USA