** Shares of RareX REE.AX rise as much as 187.5% to A$0.023, posting their biggest intraday gain since August 9, 2019
** Stock hits its highest level since May 23, 2024
** Critical minerals explorer reports an unexpected high-grade gallium find at its Cumming Range rare earth project in Western Australia
** About 74.6 mln shares change hands, marking the stock's busiest day ever
** Stock last up 175%, bringing YTD gains to 144.4%
(Reporting by Aaditya Govind Rao in Bengaluru)
((Aaditya.govindrao@thomsonreuters.com;))