TORONTO (miningweekly.com) – Cameco CEO Tim Gitzel took a chance in trying to bag uranium junior Hathor for a song in August, only for Rio Tinto to spoil the party on Wednesday when it came in with an 11% higher C$578-million bid.

The show, however, is not over yet, with the possibility that the two companies – giants in their own respects – may even team up to make a joint offer for TSX-listed Hathor.

Rio Tinto did not try blow Cameco out of the water in its unexpected move – only raising the ante to C$4.15 a share for the target in its friendly offer, compared with the C$3.75 apiece the world’s biggest uranium miner put on the table in its hostile overture.

One Canadian uranium industry executive went so far as to tell Mining Weekly Online that Rio Tinto’s bid was a “bit of a bane” and a “joke”.

The argument is that the world’s third-biggest mining company could have come in with a knock-out punch to snap up ownership of Hathor’s coveted Roughrider project, a high-grade 57-million pound deposit in northern Saskatchewan.

It didn’t, leaving the door open to a possible joint bid with Cameco.

The market certainly expects that Rio Tinto’s C$4.15 a share bid won’t be enough – Hathor’s stock soared nearly 10% in Toronto to end the day at C$4.40, a 6% premium to the offer.

New York-based First Eagle Investment Management took a roughly C$8.3-million gamble that a higher bid would arrive, revealing late on Wednesday it bought 1.9-million shares in the Vancouver-based junior during the day.

That brings its total position up to 5.65%, making it an important institutional owner in a company that has historically had more than half of its stock in the hands of retail investors. It also puts it on par with the 5.7% ownership Rio Tinto has so far amassed in Hathor.

Dundee Securities analyst David Talbot said “there is still room for another offer that could still be accretive for the acquirer. Cameco would likely have the advantage here given its ownership of two nearby uranium mills and access to a third”.

He’s put a C$5.20 a share target price on Hathor, and believes yet another company could enter the fray.

But while the focus has largely been on an “either or” outcome, with either Rio Tinto or Cameco coming out trumps, Gitzel will certainly be chewing on the idea of putting in a call to one of his counterparts at the Anglo-Australian miner to see if an offer for joint ownership might work.

Rio Tinto has not only left that door open by putting in a relatively low competing bid, but it also hasn’t yet put a deadline on its offer, saying it would remain open “for a period of not less than 35 days”.

The reasons why Cameco wants Hathor are obvious. The deposit is in its proverbial backyard, and the company is only using about one-third of the permitted capacity at the Rabbit Lake mill, located 25 km from Roughrider.

It’s busy trying to raise the permitted capacity to 16-million pounds yearly, while currently only processing 3.8-million pounds.

Cameco also announced earlier this month that all of the ore from its new Cigar Lake mine, set to start producing in 2013, will go to Areva’s McClean Lake mill, instead of Rabbit Lake.

It gets a lot of cost benefits from the new set up, but the company is left with even more overcapacity at Rabbit Lake, which rock from Roughrider could do well to fill.

Spokesperson for the Saskatoon-based firm Gord Struthers pointed out that there are other places Cameco could get ore from, such as its nearby Eagle deposit. However, there is little doubt that Hathor would make a better fit with anyone other than Cameco.

Why would Rio Tinto consider partnering with the uranium giant?

Firstly, Cameco is Canadian-owned – which a company has to be to produce uranium in Canada. This situation may change by the time Roughrider starts mining around 2017, but it's an expensive bet for even a company the size of Rio Tinto to make.

If Rio Tinto took only a majority stake in Hathor, it would make it a lot easier to get Ottawa on board if Cameco was also a large shareholder.

Secondly, Cameco has the skills to develop uranium mines in the Athabasca Basin, which can be a tricky endeavour to put it mildly.

The other reason is that Rio Tinto’s other uranium assets, in Namibia and Australia, are not performing as well as it would like.

Energy Resources Australia, in which it has a 68%, has been a perennial underperformer in the uranium sector.

And it is no secret that that the loss-making Rossing Uranium, where Rio owns 69%, needs to find new sources of ore to maintain production levels. While Rio Tinto might still be interested in buying Extract Resources for its nearby massive Husab deposit, the Chinese might beat it to the punch.

No matter if Rio or Cameco or both end up the proud owners of Hathor, investors will be keeping a close eye on TSX V-quoted Fission Energy, which owns an adjacent property.

That its share price rallied 20% on Wednesday – double what Hathor climbed – speaks volumes about expectations of a follow-up takeover for Roughrider’s new holder