Hyalophane or jaloallofane is a crystalline mineral, part of the feldspar group of tectosilicates. It is considered a barium-rich potassium feldspar. Its chemical formula is (K,Ba)[Al(Si,Al)Si2O8], and it has a hardness of 6 – 6½. The name hyalophane comes from the Greek hyalos, meaning `glass`, and phanos meaning `to appear`. An occurrence... Found on http://en.wikipedia.org/wiki/Hyalophane
Hy·al'o·phane noun [ Greek 'y`alos glass + ... to appear.] (Min.) A species of the feldspar group containing barium. See Feldspar . Found on http://www.encyclo.co.uk/webster/H/74