(Adds details on specific stocks, updates prices)
* TSX down 64.87 points, or 0.4 percent, to 16,348.07
* Eight of the TSX’s 10 main groups move lower
TORONTO, Jan 5 (Reuters) - Canada’s main stock index fell on Friday, weighed by losses among natural resource stocks as commodity prices pulled back, muting a strong weekly gain for the index.
* At 10:14 a.m. EST (1514 GMT), the Toronto Stock Exchange’s S&P/TSX composite index fell 64.87 points, or 0.4 percent, to 16,348.07. It was nevertheless on track for a 0.9-percent gain over the course of the holiday-shortened week.
* Eight of the index’s 10 main groups were in negative territory, with decliners outnumbering advancers by 2.25-to-1 overall.
* The energy group retreated 1.4 percent, while the materials group, which includes precious and base metals miners and fertilizer companies, lost 1.1 percent. The two natural resource sectors combine to account for more than 30 percent of the index’s weight.
* Oil company Canadian Natural Resources Ltd fell 1.7 percent and Nutrien Ltd, the company formed from the merger of fertilizer makers Potash Corp of Saskatchewan and Agrium Inc, lost 1.4 percent to C$68.59.
* Marijuana producers fell early before turning higher in heavy volumes. They had been rising sharply over the last week but were hit hard on Thursday when the U.S. federal government rescinded a policy that had eased enforcement of federal marijuana laws.
* Aurora Cannabis Inc rose 2.4 percent to C$13.35 after announcing its second investment in as many days.
* Prometic Life Sciences Inc 8 percent to C$1.73. (Reporting by Alastair Sharp; Editing by Nick Zieminski)