Mining giants Rio Tinto RIO.AX and BHP Group BHP.AX were down about 1% and 0.8%, respectively. Oct 27 (Reuters) - Australian shares erased early gains to edge lower on Tuesday, hit by losses in mining and gold stocks as commodity prices came under pressure and a sharp fall in supermarket major Woolworths Group, while subdued inflation data also weighed on sentiment. Woolworths WOW.AX plunged 4.5% in its sharpest drop since February on flagging a slowdown in sales as lockdowns ease, making staples sub-index .AXSJ the top loser on ASX 200.