Hilarionite is a very rare hydrated iron hydroxyarsenate sulphate, unique to this mine in the famous old district of Lavrion. This species was approved at the end of 2011. In this good-sized specimen, the hilarionite appears as botryoidal aggregates formed by small crystals, with a more intense greenish-yellow hue in some areas. The specimen was acquired by Erich Laskowsky from Anastasios Tsinidis, a well-known "strahler" (quartz hunter) of Greek origin. A fine piece from the type locality for the species.