The Pits of Hathsin was the only atium mine in the Final Empire. The Lord Ruler sent only condemned men to mine it, both because it was the only way to find the crystals (using Allomancy near atium crystals to look for the crystals would shatter them) and because he wished for the location of the atium mines to remain secret. Convicts were forced to crawl up and down narrow shafts, often over the bones of other deceased prisoners, in order to find geodes, which contained a single bead of atium. Those who were unable to find a bead of atium each week were summarily beaten to death. Kelsier was the only prisoner known to have escaped from the Pits of Hathsin, earning himself the epiphet The Survivor of Hathsin. He bore distinctive scars layered on his arms from his time in the Pits.
During the events of Mistborn: The Final Empire, Kelsier attacked the Pits of Hathsin, killing the guards and freeing the prisoners. He also used Allomancy to destroy most of the crystals which produced atium geodes in an attempt to topple the economy of the Final Empire. However, the crystals can eventually repair themselves and would have resumed producing atium in three hundred years time.
In Mistborn: The Well of Ascension , Vin believes that Zane is a Survivor of Hathsin. However, the scars on his arms are from self mutilation.