** Shares of Australia's Magnetite Mines MGT.AX jump as
much as 31.8% to A$0.725 - set for best day since Feb. 10, if
gains hold
** Co says iron ore reserves estimate increased to 1.6 bln
tonnes from 473 mln tonnes in 2021 for its Razorback iron ore
project in South Australia
** Co says upgrade due to decision to increase production
scale of project to a minimum 5 metric tonnes per annum (mtpa)
** Stock hits its highest level since Feb. 22
** MGT down ~11% this year, as of last close
(Reporting by Ayushman Ojha in Bengaluru)
((Ayushman.ojha@thomsonreuters.com;))