The designers originally planned for the building to be clad entirely with hill country limestone quarried in Oatmanville (present-day Oak Hill), about 10 miles (16 km) to the southwest. However, the high iron content of the limestone led it to discolor rapidly with rust stains when exposed to the elements. Learning of the problem, the owners of Granite Mountain near Marble Falls offered to donate to the state, free of charge, the necessary amount of sunset red granite as an alternative. To transport the red granite, the Austin and Northwestern Railroad was extended 2. 3 miles (3. 7 km) to accommodate the transportation from Granite Mountain. Due to a bend in the tracks, trains would occasionally derail, accidentally dumping some of the pink granite. Many of the fallen rocks remain in place and are a local point of interest. While the building is mostly built of the Oak Hill limestone, most of this is hidden behind the walls and on the foundations. Red granite was subsequently used for many state government buildings in the Austin area. The project's 900 workers included 86 granite cutters brought from Scotland.