Aminex, an exploration company focused on East Africa, fell after it said a planned sale of its US assets had slipped back into 2013.
The firm also said talks over a $15m loan, repayable from the proceeds of the sale of the US assets, were ongoing and were expected to be concluded "in the near future".
In the first half of 2012 Aminex announced that it had launched a marketing programme to sell its US assets so it could use the capital for exploration activities in Tanzania.
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However, it subsequently suspended the marketing of the US properties and now expects to resume it in January 2013.
It had originally planned to complete the sale of the assets in the fourth quarter.
Chief Executive Staurd Detmer said the firm's plan to focus on Tanzania was an ambitious one that would help it become one of the leading companies in the East African region.
Shares slipped 6.8% by 09:45 on Monday after the announcement.
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