http://lifesci3.arc.nasa.gov/SpaceSettlement/spaceresvol3/plsoom1.htm "Available processing techniques include hydrogen reduction of ilmenite and electrochemical and chemical reductions of silicates (Williams and Jadwick 1980, Williams 1980." "In the case of silicates, hydrogen reduction is not thermodynamically favorable and proposed processing steps include direct electrochemical reduction, reduction with carbon plus chlorine, reduction with aluminum, and reduction with methane (Kesterke 1971; Carroll 1983; Colson and Haskin, immediately following; Williams and Erstfeld 1979; Anthony et al. 1988; Rosenberg et al., immediately preceding)."