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Hyalophane  (variety of Feldspar)
Current inventory:  0 gems
 

Chemistry:  (K,Ba)Al(Si,Al)₃O₈

Discovered in 1855;   IMA status: Valid (pre-IMA; Grandfathered).
The name Hyalophane is from the Greek words hyalos - "glass" and phanos - "to appear" in allusion to the transparency of its crystals.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/J.06-50

Nickel-Strunz 10th Ed. ID:

9.FA.30

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H₂O
A : Tektosilicates without additional non-tetrahedral anions

Related to:

Feldspar Group;

Celsian-Hyalophan Series,

Hyalophane-Orthoclase Series

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Crystals similar to Adularia or Orthoclase, to 20 cm; also granular or massive.

Twinning:

Commonly simple twins according to the Carlsbad, Manebach, or Baveno laws.

Physical Properties

Cleavage:

[001] Perfect, [010] Imperfect

Fracture:

Uneven, Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

6.0 - 6.5

Density:

2.58 - 2.82 (g/cm³)

Luminescence:

None

Radioactivity:

Barely Detectable, GRapi = 9.71 (Gamma Ray American Petroleum Institute Units)

Optical Properties

Color:

Colorless, White, pale Yellow, Red

Transparency:

Transparent to Translucent

Luster:

Vitreous

Refractive Index:

1.542 - 1.547  Biaxial ( - )

Birefringence:

0.005

Dispersion:

Weak; r > v

Pleochroism:

None

Occurances

Geological Setting:

Typically associated with metamorphosed manganiferous rocks or in mineral deposits rich in manganese.

Common Associations:

Manganiferous Epidote, Rhodonite, Rhodochrosite, Spessartine, Manganiferous Tremolite, Plagioclase, Analcime.

Type Locality:

Lengenbach Quarry, Im Feld (Imfeld; Feld; Fäld), Binn Valley, Wallis (Valais), Switzerland

Year Discovered:

1855

View mineral photos:

Hyalophane Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Hyalophane is very rare gemstone and a member of the Feldspar Group of minerals that also includes Albite, Amazonite, Andesine, Anorthite, Bytownite, Hyalophane, Labradorite, Moonstone, Oligoclase, Orthoclase, Sanidine and Sunstone. It is usually found as translucent to opaque crystals of colorless, white or pale yellow. Crystals are rarely found clean enough for faceting.

The only current source of these rare crystals is Busovaca, Bosnia.
 

  
Hyalophane gems for sale:

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