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Hyalophane
Chemical Formula	(K,Ba)[Al(Si,Al)Si2O8]
Species	Silicates
Crystal System	Monoclinic
Mohs Scale	6
Specific Gravity	2.81
Color	Colorless, yellow, white, red
Streak	White
Luster	Vitreous
Refractive Index	n = 1.542 n = 1.545 n = 1.547
Diaphaneity	Transparent to translucent
Cleavage	perfect, imperfect
Fracture	Conchoidal
Crystal Habit：Crystalline – fine – occurs as well-formed fine sized crystals; massive – uniformly indistinguishable crystals forming large masses

Hyalophane or jaloallofane is a crystalline mineral with chemical formula (K,Ba)[Al(Si,Al)Si₂O₈] and a hardness of 6 – 6?. It is part of the feldspar group of tectosilicates, and is considered a barium-rich potassium feldspar. Hyalophane comes from the Greek hyalos, meaning "glass", and phanos meaning "to appear".

An occurrence of hyalophane was discovered in 1855 in Lengenbach Quarry, Imfield, in the municipality of Binn, Switzerland. The mineral is found predominantly in Europe, with occurrences in Switzerland, Australia, Bosnia, Germany, Japan, New Jersey, and the west coast of North America.

Hyalophane has a monoclinic crystallography, with cell properties a = 8.52 ?, b = 12.95 ?, c = 7.14 ?, and β = 116°. Optically, the material exhibits biaxial birefringence, with refractive index values of n_α = 1.542, n_β = 1.545, and n_γ = 1.547 and a maximum birefringence of δ = 0.005. It has weak dispersion and low surface relief.