Gilalite (inclusions in Quartz)
Current inventory:  0 gems
 

  
Gilalite is named after Gila County, Arizona, USA where it was discovered at the Christmas Mine in the Banner District of the Dripping Spring Mountains.

Discovered in 1979; IMA status: Valid (IMA approved 1980)

Chemistry

Chemical Formula:

Cu₅Si₆O₁₇ · 7(H₂O)  (in Quartz - SiO₂)

Hydrated Copper Silicate (in Quartz)

Molecular Weight:

884.34 gm

Composition:

Copper

35.93 %

Cu

44.97 %

CuO

Silicon

19.06 %

Si

40.77 %

SiO₂

Hydrogen

1.60 %

H

14.26 %

H₂O

Oxygen

43.42 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/D.06-10

Nickel-Strunz 10th Ed. ID:

9.HE.05

9 : SILICATES (Germanates)
H : Unclassified silicates
E : With Cu, Zn

Related to:

Chemically very similar to Apachite Cu₉Si₁₀O₂₉•11(H₂O)

Varieties:

None

Synonyms:

IMA1979-021

Crystal Data

Crystallography:

Monoclinic (probable)

Crystal Habit:

As spherules of radial fibers, to 0.3 mm.

Twinning:

None

Physical Properties

Cleavage:

n/a

Fracture:

n/a

Tenacity:

Waxy or gummy

Moh's Hardness:

2.0

Density:

2.72 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Chrysocolla-green, inclining to pale blue-green.

Transparency:

Transparent to Translucent

Luster:

Nonmetallic

Refractive Index:

1.560 - 1.635  Biaxial ( - ) 

Birefringence:

0.075

Dispersion:

None

Pleochroism:

Weak in drab grayish green

Occurances

Geological Setting:

A retrograde metamorphic or mesogene mineral formed at the expense of a prograde calc-silicate and sulfide assemblage; in tactites, commonly incrusting fractures; also filling cracks or interstices in diopside grains (Christmas, Arizona, USA).

Common Associations:

Kinoite, Apachite, Stringhamite, Junitoite, Clinohedrite, Xonotlite, Diopside, Apophyllite, Calcite, Tobermorite (Christmas, Arizona, USA).

Common Impurities:

Mn, Mg, Ca

Type Locality:

Christmas Mine (Red Bird shafts; Inspiration Mine; Hackberry shafts), Christmas, Christmas area, Banner District, Dripping Spring Mts, Gila County, Arizona, USA

Year Discovered:

1979

View mineral photos:

Gilalite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Gilalite is a rare hydrated copper silicate that was discovered in 1979 as green to blue-green spherules of radial fibers to 0.3mm in diameter at the Christmas Mine in Gila County, Arizona, USA. Minute, transparent crystals have also been found, but too small for faceting. Gilalite is never a faceted gem on its own but is an unusual and very attractive inclusion in Quartz. As a gem material Gilalite was discovered at São José da Batalha, Salgadinho, Borborema mineral province, Paraíba, Ceará, Brazil in August, 2004 as beautiful inclusions in Quartz. It occurs as small spherules or accicular fibers of light to dark green, blue-green and blue. Quartz with Gilalite inclusions is also known as "Paraiba Quartz" due to the color similarities to Paraiba variety of Tourmaline; or "Medusa Quartz" because under magnification, the small balls of Gilalite suspended in Quartz resemble the shape of a floating jellyfish named Medusas Rondeau. GIA had an article in the Fall 2005 (Volume 41, Issue 3) of Gems & Gemology about Medusa Quartz.

Locations for finding Gilalite: São José da Batalha, Salgadinho, Borborema mineral province, Paraíba, Ceará, Brazil; Lavrion District slag localities, Lavrion District, Attiki Prefecture, Greece. In the USA: Christmas Mine, Banner District, Dripping Spring Mountains, Gila County, Arizona and and the Lonestar deposit, near Safford, Graham County, Arizona; Boss Mine, Goodsprings District, Nevada.
 

  
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