Gilalite is a copper silicate mineral with chemical composition of Cu5Si6O17·7(H2O).[4]

Gilalite
Blue Gilalite crystals
General
CategorySilicate mineral
Formula
(repeating unit)
Cu5Si6O17·7(H2O)
IMA symbolGil[1]
Strunz classification9.HE.05
Crystal systemMonoclinic
Unknown space group
Unit cella = 13.38, b = 19.16
c = 9.026 [Å]; β ≈ 90°; Z = 4
Identification
Formula mass884.3 g/mol
ColorBlue green, green
Crystal habitRaidiating fibrous in spherules
TenacityWaxy or gummy
Mohs scale hardness2
LusterNonmetallic
StreakLight green
DiaphaneityTranslucent
Specific gravity2.72
Optical propertiesBiaxial (-)
Refractive indexnα= 1.560 nβ=1.635 nΎ= 1.635
Birefringenceδ = 0.075
References[2][3][4]

It occurs as a retrograde metamorphic phase in a calc-silicate and sulfide skarn deposit. It occurs as fracture fillings and incrustations associated with diopside crystals.[3] It is commonly found in the form of spherules of radial fibers.

Gilalite inclusions within a quartz crystal from Juazeiro do Norte, Ceara State, Brazil (size: 7.1 x 4.7 x 2.7 cm)

It was first described for an occurrence in the Christmas porphyry copper mine in Gila County, Arizona in 1980 along with the mineral apachite.[5] It derives its name from this locality. It has also been reported from the Goodsprings District, Clark County, Nevada; Juazeiro do Norte, Ceara State, Brazil and a slag area in Lavrion District, Attica, Greece.[4]

References

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  1. ^ 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.
  2. ^ gilalite - Wolfram Alpha
  3. ^ a b Handbook of Mineralogy
  4. ^ a b c Gilalite: Gilalite mineral information, Mindat.org
  5. ^ F.P. Cesbron and S.A. Williams; March 1980;"Apachite and gilalite, two new copper silicates from Christmas, Arizona" Mineralogical Magazine, Vol. 43, pp. 639-41