Gilalite
Gilalite is a copper silicate mineral with chemical composition of Cu5Si6O17·7(H2O).[4]
| Gilalite | |
|---|---|
 Blue Gilalite crystals | |
| General | |
| Category | Silicate mineral |
| Formula (repeating unit) | Cu5Si6O17·7(H2O) |
| IMA symbol | Gil[1] |
| Strunz classification | 9.HE.05 |
| Crystal system | Monoclinic Unknown space group |
| Unit cell | a = 13.38, b = 19.16 c = 9.026 [Å]; β ≈ 90°; Z = 4 |
| Identification | |
| Formula mass | 884.3 g/mol |
| Color | Blue green, green |
| Crystal habit | Raidiating fibrous in spherules |
| Tenacity | Waxy or gummy |
| Mohs scale hardness | 2 |
| Luster | Nonmetallic |
| Streak | Light green |
| Diaphaneity | Translucent |
| Specific gravity | 2.72 |
| Optical properties | Biaxial (-) |
| Refractive index | nα= 1.560 nβ=1.635 nΎ= 1.635 |
| Birefringence | δ = 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
- 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.
- gilalite - Wolfram Alpha
- Handbook of Mineralogy
- Gilalite: Gilalite mineral information, Mindat.org
- 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
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