An ancient sample of pharmacolite, whose Greek root name means “poisoned stone” due to the presence of arsenic in this mineral with the formula CaH(_AsO4),_H2OThis specimen is associated with uncrystallized tetrahedrite and comes from the former Glückauf mine belonging to the Sainte Marie aux Mines district in the Haut Rhin region of Alsace.
The Glückauf mine (or Glück-Auf, which means “good luck” in German, the German miners’ expression of salvation) was mined for silver from the 15th to the 19th century.
In the Bulletin du Service de la carte géologique d’Alsace et de Lorraine of 1968 (tome 21, n°2, article on the description and mineralogy of mines in the Sainte-Marie-aux-Mines region by Pierre Fluck), it is even said that:“In 1772, Glückauf provided arborescent native silver of such beauty that it was not smelted, but sold as is“.
Not to be confused with the Glückauf mine in Germany (Sonderhausen, Thuringia).   Video of this pharmacolite and tetrahedrite from Sainte-Marie-aux-Mines :