Hungary has some really outstanding localities for unique hyalites: Monok, Gyöngyössolymos, and recently Tarcal. Specimens from this locality tend to be the biggest, glassiest and the best from Hungary! The downside is that the andesite quarry uses explosives, which damages most opals before anyone had the chance to collect them. Plus the quarry is now closed for mineral collectors, meaning very small amount of acceptable specimens make it to the market every year (if any). Hyalites glow green in UV-C light (short wave UV light), and the white/yellow Calcite, Aragonite show medium fluorescence under UV-A light: usually bluish, yellow or white.