(Adds details on specific stocks, updates prices)
* TSX up 9.16 points, or 0.06 percent, at 16,105.23
* Half of the TSX's 10 main groups move higher
TORONTO, Dec 11 (Reuters) - Canada's main stock index inched higher in morning trade on Monday, boosted by gains for materials stocks including fertilizer companies, while gold miners moved in both directions and railway stocks weighed.
* At 9:51 a.m. ET (1451 GMT), the Toronto Stock Exchange's S&P/TSX composite index was up 9.16 points, or 0.06 percent, at 16,105.23.
* Half of the index's 10 main groups were in positive territory, with advancers outnumbering decliners by a 1.4-to-1 ratio.
* Potash Corp was up 1.4 percent to C$24.68 and Agrium Inc added 1.3 percent to C$138.27 as the two fertilizer companies move closer to a merger.
* The materials group, which includes precious and base metals miners and fertilizer companies, added 0.6 percent.
* The heavyweight energy and financials groups were both flat, while industrials fell 0.2 percent as Canadian National Railway Co slipped 0.4 percent to C$102.71.
* Prometic Life Sciences Inc was up 7.1 percent at C$1.36 after a British health regulator gave one of its drugs a promising designation.
* Shopify Inc added 2.4 percent to C$132.59 after the commerce software company was added to several S&P/TSX sub-indices.
* Several gold miners advanced even as the price of bullion steadied, with Iamgold Corp up 4.0 percent to C$6.76 and Yamana Gold Inc rising 2.2 percent to C$3.23. Kirkland Lake Gold Ltd, meanwhile, was down 3.8 percent at C$17.24. (Reporting by Alastair Sharp; Editing by Andrew Hay)