Hyalophane - Encyclopedia
Class : Silicates
Subclass : Tectosilicates
Crystal system : Monoclinic
Chemistry : (K,Ba)Al(Al,Si)3O8
Rarity : Uncommon
Hyalophane is a rare mineral from the feldspar group in which it forms two series with orthoclase and celsian. It is an accessory mineral of manganiferous metamorphic rocks and manganiferous pyrometasomatic deposits, which is also found in carbonate rocks and Alpine clefts. Its name comes from the Greek hualos (glass) and phanos (shiny) or phainein (to appear), in allusion to its transparent and shiny appearance, similar to glass. Hyalophane forms crystals similar to those of adularia or orthoclase, frequently rhombohedral in appearance, commonly twinned like orthoclase, which can reach 20 cm. Hyalophane is colorless to whitish, straw yellow, sometimes pink to orange-yellow, exceptionally yellow-brown.
Main photo : Hyalophane from Zagradski Potok Mine, Bosnia-Herzegovina © Jordy Fabre
Hyalophane in the World
Twinning
Twins are common for this mineral species.
Fakes and treatments
No fakes recorded for this mineral species.
Hardness : 6 to 6.5
Density : 2.54 to 2.57
Fracture : Irregular
Streak : White
TP : Translucent to transparent
RI : 1.542 to 1.547
Birefringence : 0.005
Optical character : Biaxial -
Pleochroism : None
Fluorescence : Pink
Solubility : Insoluble
Magnetism : NoneRadioactivity : None