Decreases in domestic production of construction materials (cement, construction sand and gravel, and crushed stone), as well as gypsum, were large compared with production during the third quarter of 2012 – likely owing to a seasonal decline in construction compared with previous quarters of 2012 – according to USGS in its latest Mineral Production Report.
The U.S. Census Bureau and the U.S. Department of Housing and Urban Development (2013) reported privately owned housing unit starts increased 33 percent in the fourth quarter of 2012 compared with that of the same period in 2011, and increased by approximately 15 percent in the fourth quarter of 2012 compared with that of the third quarter of 2012. The U.S Census Bureau (2013) also reported that the seasonally adjusted value of construction in 2012 was 9.2 percent above that in 2011.
Copper production in the United States increased from the third quarter to the fourth quarter; increases in Arizona, New Mexico and Nevada were partially offset by lower production in Utah.
Molybdenum production in the United States decreased by 12 percent in 2012 from that in 2011 primarily owing to reduced production from the Thompson Creek Mine in Idaho. The 7 percent increase of phosphate rock production from 2011 to 2012 was the result of strong demand during the agricultural growing season earlier in the year.
Although zinc production was also lower during the first three quarters of 2012, mainly owing to reduced milling rates and lower zinc ore grades at the Red Dog Mine in Alaska and the temporary closure of the Lucky Friday Mine in Idaho, production increased in the fourth quarter 2012 compared with the fourth quarter of 2011 and the third quarter of 2012.
Closure of the Lucky Friday Mine also was responsible for lower silver production; silver production increased in the fourth quarter of 2012 compared with that of the third quarter.