By Brenton Cordeiro Feb 8 (Reuters) - Aquarius Platinum reported a 24 percent drop in core profit for the first half, but said it was able to bring down costs by about a third, sending the miner's shares up as much as 10 percent. Aquarius, the world's fourth largest platinum producer, said profitability at its mines was $22 million for the six months ended Dec. 31, compared with $29 million a year earlier, due to tough operating conditions at its South Africa mines and lower platinum prices.