** Jefferies raises valuation of diversified miner South32's S32.AX 50% interest in a joint venture to develop critical mineral resources at the Amber mining district in Alaska to A$1.31 billion($863.30 million) from A$1.13 billion
** The U.S. government announces a $35.6 million investment in Trilogy Metals TMQ.TO, S32's JV partner
** Brokerage says federal stake in the project enhances execution prospects and fastens development pipeline
** Jefferies now expects mining to start in late CY2033, compared to earlier projection of CY2035
** Brokerage rates S32 as 'buy' with PT of A$3.30
** Median PT of 16 analysts is A$3.10, as per LSEG-compiled data
** YTD, S32 shares down 13.8%
($1 = 1.5198 Australian dollars)
(Reporting by Nichiket Sunil in Bengaluru)
((Nichiket.Sunil@thomsonreuters.com))