The company, through an indirect wholly-owned Canadian subsidiary, has made an offer to buy Hathor shares for C$4.70 ($4.51) in cash per share.
Rio Tinto’s recommended offer values Hathor at about C$654m ($627.6m) on a fully-diluted basis.
The Hathor board of directors has already recommended that Hathor shareholders accept and tender their common shares to Rio Tinto’s offer.
Hathor is focused on exploration projects in the Athabasca basin of northern Saskatchewan, Canada.
