Hecla made a so-called white-knight offer to rescue Aurizon from the earlier hostile bid by Alamos Gold Inc. (TSX:AGI), which owns a 16 per cent stake in Aurizon.
One condition of the Hecla offer, however, is approval from two-thirds of Aurizon shareholder votes at a meeting.
That means Alamos, which has said it was looking to increase its stake in Aurizon, could block the Hecla deal with only about one-third of Aurizon's shares, or possibly less if some other shareholders sit on the sidelines.
"The changes to Alamos' bid and public statements of their intent make it clear that Alamos simply wants to impede shareholder choice by denying Aurizon's shareholders any opportunity to consider other transactions such as the Hecla arrangement," said George Brack, chairman of the special committee of the board at Aurizon.
"The new rights plan does not prevent Alamos or any other party from making a better offer. It simply ensures that Aurizon's shareholders will have an opportunity to make a choice."
Under the rights plan, which could be overturned by a regulator, Aurizon's board could trigger a "poison pill" if any bidder or group working together acquires 20 per cent or more of the company's stock. It also says the defence wouldn't be triggered if the offer is made to all shareholders other than the bidder and with a threshold of acceptance by at least 50 per cent of the independent stock.
Last week, Alamos waived the minimum tender condition of its offer primarily because "based on expressions of support from several large shareholders of Aurizon received following the Hecla proposal, Alamos fully expects to receive at least an additional 17.3 per cent of the outstanding Aurizon shares in order to defeat the merger of Aurizon with Hecla as proposed by the Aurizon board."
The change by Alamos followed Aurizon's friendly deal with Hecla Mining valued at $796 million in stock and cash.
Aurizon has eight properties in Quebec, including the Casa Berardi gold mine, as well as several development and exploration projects.
Alamos, which has its head office in Toronto, has a mine and mineral rights in Mexico and an advanced development project in Turkey while Hecla has mines in Alaska and Idaho, as well as projects in the U.S. and Mexico.
Aurizon CEO George Paspalas has said the Hecla offer was better than the one from Alamos, both because there was more cash involved and because a combined Hecla-Aurizon would make more long-term sense.
Hecla's cash and stock offer, valued at $4.75 per Aurizon share (TSX:ARZ), is 10 cents more than a hostile bid by Alamos Gold Inc. (TSX:AGI) which was valued at $4.65 per share when it was announced.
And the $513.6-million cash component is almost $210 million above the cap in the Alamos stock and cash bid.
Aurizon shares were down three cents at $4.52 in trading on the Toronto Stock Exchange, while Alamos shares were down two cents at $14.52.
Hecla shares were up two cents at US$4.27 on the New York Stock Exchange.