* TSX ends down 0.3% at 34,857.34

* Materials sector loses 2.1% as gold falls

* Alamos Gold ( AGI ) tumbles 18.4%

* OSFI lowers big bank capital requirement

(Updates at market close)

By Fergal Smith

TORONTO, June 19 (Reuters) - Canada's main stock index fell

on Friday to post a slight weekly decline, as a drop in gold

prices weighed on metal mining shares.

The Toronto Stock Exchange's S&P/TSX Composite index

ended down 111.92 points, or 0.3%, at 34,857.34,

extending its pullback from a record closing high on Tuesday.

For the week, the index was down 0.2%.

* Global shares also dipped after U.S. and

Iranian negotiators called off peace talks. The U.S. stock

market was closed for the Juneteenth holiday.

* "Financial markets grappled with two nearly equal and

offsetting forces this week," Douglas Porter, chief economist at

BMO Capital Markets, said in a note, pointing to the preliminary

peace agreement in the Middle East and a more

hawkish-than-expected message from the Federal Reserve.

* The price of gold fell 1.2% as a hawkish Fed helped

underpin the U.S. dollar in recent days.

* The materials sector, which includes metal mining shares,

fell 2.1%.

* Shares of Alamos Gold ( AGI ) tumbled 18.4% after the

miner cut its production forecast for the second quarter.

* Capstone Copper ( CSCCF ) has identified significant

groundwater impacts across its Mantos Blancos copper mine in

northern Chile that it aims to mitigate as part of a major

expansion, according to company materials reviewed by Reuters.

The company's shares ended 4.1% lower.

* Canada's banking regulator, the Office of the

Superintendent of Financial Institutions, lowered the capital

requirement for the country's biggest banks for the first time

in three years, a move that will allow them to lend more.

* Still, the heavily weighted financials sector

dipped 0.1%.

* The price of oil clawed back some recent declines

to rise 1.2%. Energy added 0.7%.

* MDA Space ( MDA ) shares ended 6.3% higher after the

space technology firm agreed to buy U.S.-based Blue Canyon

Technologies from RTX's Raytheon business for $620

million in cash.