Feb 11 (Reuters) - Canada's main stock index opened

lower on Tuesday due to losses led by mining shares as investors

assessed new U.S. tariffs, while e-commerce giant Shopify ( SHOP )

rose 4.8% after beating fourth-quarter revenue

estimates.

At 9:31 a.m. ET (1431 GMT), the Toronto Stock Exchange's

S&P/TSX composite index was down 0.26% at 25590.95.