Madagascar's interim president, who seized power in the Indian Ocean island nation last month, has unveiled a 300 kg (661 lb) gemstone that he said had been found in the presidential palace.The dark boulder, streaked with shimmering green crystal, was shown on Tuesday evening inside the Ambohitsorohitra State Palace in the capital Antananarivo.The stone, described as an "emerald in matrix," still needs expert analysis to determine the size and quality of the emerald embedded within."This is a