Curium is produced in small quantities in nuclear reactors, and by now only kilograms of it have been accumulated for the 242Cm and 244Cm and grams or even milligrams for heavier isotopes. This explains the high price of curium, which has been quoted at 160–185 USD per milligram, with a more recent estimate at US$2,000/g for 242Cm and US$170/g for 244Cm. In nuclear reactors, curium is formed from 238U in a series of nuclear reactions. In the first chain, 238U captures a neutron and converts into 239U, which via β− decay transforms into 239Np and 239Pu.