Haüyne is a rare mineral and an extremely rare gemstone. Recently, the authors studied a large number of faceted haüynes from the Eifel district of Germany. The R.I. and S.G. data were consistent with those reported in the literature, and the samples’ identity was confirmed by Raman spectrometry, with the key maxima at 543 and 988 cm^-1. EDXRF analyses revealed potassium and iron, as well as the major and minor elements expected in haüyne. Although mineral inclusions were uncommon, apatite and augite were identified, and negative crystals (often surrounded by healed fractures) were seen in approximately one-third of the stones. Short needles and fine, dust-like particles were present in about half the samples. Paraffin wax was identified in some open fissures.

(Caption)The haüynes in this brooch (with diamonds and a pink sapphire) range from 0.095 to 0.173 ct. Photo courtesy of Della Valle.