The value of nonfuel mineral production in New Jersey in 2001 was estimated to be $348 million, up nearly 20% from 2000. According to preliminary figures, in 2001, 31 million metric tons of crushed stone were produced, for a total value of $218 million, up $174 million from the previous year. Other mineral resources mined or recovered included construction sand and gravel (17.9 million metric tons, worth $94.8 million), industrial sand and gravel (1.69 million metric tons, worth $35.5 million), common and fire clays, greensand, peat, titanium, and zircon concentrates. New Jersey continued to be the only state that produced greensand, also known as the mineral glauconite, which is processed and sold mainly as a water-softening filtration medium to remove soluble iron and manganese from well water. A secondary use is as an organic conditioner for soils.