Haüyn/Hauyne green (sodalite)

Green hauyne is an extremely rare variety of sodalite, belonging to the tectosilicate group. This mineral is characterized by its high sodium and sulfur content and its characteristic color, which ranges from greenish blue to bright green. Hauyne crystallizes in the cubic system and is commonly found in volcanic rocks such as phonolites or nephelinites, where it forms in the presence of alkali elements. One of the most interesting features of green hauyne is its pronounced fluorescent response. Under shortwave UV radiation, it often exhibits intense orange-red fluorescence, while under longwave UV radiation it may fluoresce weakly to pink or orange. This optical property is important in identifying and distinguishing it from visually similar minerals. From a gemological perspective, green hauyne is valued for its vitreous luster, relative transparency, and high refractive index (1.49–1.51), which contributes to its optical brilliance. Its hardness on the Mohs scale ranges between 5.5-6, making it suitable for collector's purposes or jewelry with careful handling. Due to its rarity and limited occurrence, green hauyne is highly sought after among mineralogists and gemologists.