Small caps round-up: Aminex, Solo, Firestone Diamonds ...

Oil and gas companies Aminex and Solo Oil took a hit on Tuesday morning after the first stab at drilling their shared Ntorya-1 exploration well in the Ruvuma Basin onshore in Tanzania proved disappointing.

Data will now be recorded to determine whether or not to drill further. Aminex shares fell 38.27% to 3.02p, while Solo lost 32% to 0.51p. Tullow Tanzania also holds a 25% stake in the well.

Firestone Diamonds, the AIM-quoted mining and exploration company, has concluded its first diamond tender of 2012, where all available stock was sold. The firm also reported good progress at the Liqhobong Mine, with plant throughput increasing from 0.4m tonnes to 0.6m tonnes per annum at plant one on the site. At the firm's BK11 mine in Botswana, challenges remain in terms of the liberation of diamonds from the secondary crushing circuit of the plant. "We remain cautiously optimistic for the months ahead," the firm said. Shares fell 7.77% to 11.88p.

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Horizonte Minerals, an exploration and development company focused in Brazil, has completed the acquistion of 100% of the Vila Oito and Floresta nickel laterite projects. The total consideration for the acquisition was 8.5m new ordinary shares in Horizonte, which will be issued to Lara Exploration, from which the projects were purchased. Lara has agreed not to dispose of the consideration shares for a minimum of 12 months following their date of admission to trading on AIM.

Investment trust Crystal Amber Fund, the activist investor in recovery plays, said its net asset value per share (NAV) at the end of January had shot up to 101.99p from 88.72p at the end of December.