BUZZ-Antofagasta: Buys 50 pct stake in Barrick Chilean copper mine
** Copper miner Antofagasta (Other OTC: ANFGF - news) down 1.9 pct after buying a 50 pct stake in Barrick Gold (Hanover: ABR.HA - news) 's Zaldivar mine in Chile for $1 bln
** Antofagasta would become the operator of copper mine Zaldivar
** Stock second-largest loser on FTSE 100, hovering near 6-yr lows first seen on Monday, with a third of its 30 day avg volume having gone through in the first hour of trade
** Broader UK mining sector also down 0.69 pct
** Goldman Sachs (NYSE: GS-PB - news) cut PT on co to 490p from 500p, keep "sell" rating, citing the company's valuation
** Co trades at 22.6x its earnings for the next 12 months, a 50 pct premium to the median of its peers, according to Thomson Reuters data (venkateshasoumithri.mamidipudi.thomsonreuters.com@reuters.net)