VANCOUVER — The board of Aurizon Mines Ltd. has adopted a new shareholder rights plan, saying it wants to prevent Alamos Gold Inc. from using its voting power to defeat a better takeover offer from a rival company. Alamos already owns 16% of Aurizon and has offered to buy up the rest of its stock. Aurizon’s board is supporting a rival offer from Hecla Mining Co. and said Monday that its new rights plan will ensure all shareholders are treated equally. Comments by Alamos chief executive John McCluskey in a television interview on March 5 suggested his company is attempting to gather enough shares to block the Hecla bid, Aurizon said.Alamos has dropped a requirement that at least two-thirds of Aurizon’s shares be tendered to its offer and that could mean it will be able to torpedo any deal with less than a majority of Aurizon’s stock. A week ago, Hecla Mining announced a friendly takeover offer for Aurizon that was valued at $796-million, although only $513.6-million of that would be in cash. Aurizon CEO George Paspalas 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, is 10 cents more than a hostile bid by Alamos Gold Inc. 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.