Twin Peaks Quarry is owned and operated by
Arizona Portland Cement Co. and is an
important source of the limestone used to make
cement. pdf 
Although Arizona is known as the copper state, many other metals and materials are mined here.
Viewed March, 2019.
LINEUP
Twin Peaks Quarry:
Producer in Pima county in Arizona, United States with commodities Limestone, General, Stone, Crushed/Broken, Cement Rock. usgs
Plant manager Dave Bittel said Arizona Portland Cement has been mining the easternmost of the two peaks for limestone deposits since 1949. post