First find of alpersite in Bulgaria

First find of alpersite for Bulgaria is reported. The specimens have been collected from an abandoned exploration drift in the Lozen ore field, Eastern Rhodopes. The studied crystals have prismatic habit and typical for the mineral pale blue color. XRF, XRD, SEM-EDS and DSC-TG analyses have been used to characterize the samples. The obtained crystal chemical formula (Mg0.46Cu0.39Zn0.15)SO4•7H2O reveals a significantly higher amount of Zn2+, than previously reported for this mineral composition. This affects the structural parameters and the thermal behavior of the studied specimens. In order to clarify the conditions of formation, temperature and humidity measurements have been carried out in the accessible part of the drift mine.