Picropharmacolite and arsenolite from the Mareshnitsa ore occurrence, Eastern Rhodopes - new minerals for Bulgaria

New for Bulgaria arsenic minerals picropharmacolite and arsenolite from the Mareshnitsa ore occurrence, Eastern Rhodopes are presented. Their formation is due to the oxidation of arsenopyrite, which is abundant in the samples. The composition of the picropharmacolite from Mareshnitsa differs from the picropharmacolite from other deposits around the world. It is characterized by relatively few impurities and excess of Mg, which substitute part of Ca. This is resulting in smaller a parameter of the unit cell. The presence of these two new arsenic minerals sheds additional light on the behaviour of arsenic in the area.