The ore extracted at the Tellure Park mine consisted of silver galena, a lead sulfide (PbS) that contained 2-3% silver. The galleries were also made of blende and secondary metalliferous minerals, such as gray copper, pyrite, and chalcopyrite. The galena that impregnated the rocky walls was sometimes mixed with a matrix of quartz and barite. The miners exploited the veins that first emerged from the walls and then dug through them. The hardness of the rock made the operation tedious, and the progression was slow (0.33 to 1.64 ft / 10 to 50 cm per day). The veins' thickness varied between 8 to 11 inches (20 to 30 cm) but could reach up to 5 ft (1.50 m).