The three Stonebreaker brothers were instrumental in building the Deep Workings of Cerro Rico. Newcomen Stonebreaker is the youngest of the |brothers, followed by Droli and Stronin Stonebreaker the eldest of the three. They journeyed from the Erinthor Mountains at the bequest of House Vetrini to upgrade the mines of Cerro Rico. approximately ten years ago, after the Vetrini agreed to a incredibly payment to lease their mining expertise.
Upon arriving at the mine, they were quickly horrified by the treatment of the miners, however their soon discovered that quitting and returning east was not an option. Orignally they were also somewhat mollified when Overseer Lucius Vetrini convinced them that the very reason they had been retained was to address the horrific conditions.
Newcomen Stonebreaker immediately attacked problems with flooding and ventilation which was the leading cause of death of miners, a problem which he greatly solved vis his Mine Engines. Stronin Stonebreaker also managed to map and quantify the mithril seems that had been discovered and developed a formula for predicting where additional seams might be located. For awhile the brothers thought they were actually having a positive impact on operations, however soon after Lucius announced plans to delve still deeper into the mountain in search of the seams that Stronin had predicated. There was no way to do this safely, even with Newt's inventions.
At this point the brothers had enough and resigned. Where they discovered they were not actually free to leave. Their imprisonment was comfortable, but it was imprisonment none the less. After years of work, and despite the huge increase in mithril and silver production, the conditions are actually worse then when they began. At least until the mine disaster.