** Shares of Rio Tinto fall as much as 2.1% to A$119.51

** World's largest iron ore miner says it shipped weaker-than-expected 84.5 mln tonnes of ore from its Western Australia operations during the third quarter, of which 19% accounted to ower-grade, lower-margin product called SP10

** Co says it is reviewing its product strategy at flagship Pilbara iron ore operations

** Rio flags that investor should continue to expect SP10 volumes to remain high for several years

** Rio now expects Pilbara iron ore unit cash costs to be in the upper half of its $21.75 to $23.50 atonne estimate due to inflation being at the higher end of co's expectations

** Rio's current stock drop is also in line with broader fall in iron ore futures with mining index down 0.9%

** Co has been criticised by investors for offering an unnecessarily full price to Arcadium shareholders and has followed this up with a disappointing SepQ prodn report — Citi

** Stock has fallen 10% YTD, as of last close

(Reporting by Rishav Chatterjee in Bengaluru)

((Rishav.Chatterjee@thomsonreuters.com))