** Magnetite Mines MGT.AX surges as much as 310.4% to A$0.291; marks biggest ever intra-day pct gain
** Stock hits highest since July 26, 2024
** Mineral explorer finds rare earth element mineralisation at Ironback Hill Project, South Australia's northeast
** About 13.1 mln shares traded - 67.6x 30-day avg - in stock's busiest day ever
** MGT last up 69%, takes YTD gains to 6%
(Reporting by Ananya Verma in Bengaluru)
((ananya.verma@thomsonreuters.com;))