Critical Metals is a momentum stock, and incredibly hard to value.Critical Metals (CRML 8.60%) stock, a start-up miner of rare-earth elements, tumbled 9.8% through 1:35 p.m. ET this morning despite reporting some apparently good news for shareholders.Drilling at its exploratory Tanbreez Rare Earth Project in Greenland, Critical Metals has found evidence of minable quantities of yttrium, cerium, gallium, and hafnium, as well as zirconium, niobium, and tantalum. What this means for investorsThe company says t ...