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Gilalite (inclusions in Quartz)
Current inventory:  0 gems
 

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

Discovered in 1980;   IMA status: Valid (pre-IMA; Grandfathered).
Gilalite is named after Gila County, Arizona, USA where it was discovered at the Christmas Mine in the Banner District of the Dripping Springs Mountains.

Classification

Mineral Classification:

Silicates

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

Crystal Data

Crystallography:

Monoclinic - (space group unknown)

Crystal Habit:

As spherules of radial fibers, to 0.3 mm.

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

n/a

Tenacity:

Waxy or Gummy

Hardness (Mohs):

2.0

Density:

2.72 - 2.82 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Translucent Green, Blue-Green, Chrysocolla-Green to pale Blue-Green

Transparency:

Transparent or Translucent

Luster:

Nonmetallic

Refractive Index:

1.560 - 1.635  Biaxial ( - )

Birefringence:

0.0750

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).

Type Locality:

Christmas Mine, Christmas area, Banner District, Dripping Spring Mts, Gila County, Arizona, USA

Year Discovered:

1980

View mineral photos:

Gilalite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Gilalite is never a faceted gem on its own but is an unusual and very attractive inclusion in Quartz. It was discovered as 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. As a gem material however, Gilalite was discovered in Ceará, Northeast Region, 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 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.
 

  
Gilalite in Quartz gems for sale:

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