Studies were carried out on white coral stone used for the construction of the Hukuru Mosque, Male, the most important monument of Maldives. The stone is composed of the mineral aragonite, CaCO3, and is highly porous. Porosity and water absorption properties of the stone were studied. High rainfall and the tropical climate of the region have contributed much toward the deterioration of the coral stone. Surface of the stone continuously lashed with heavy rains erodes and becomes very rough. Algae grows excessively on coral stone and penetrates deep into its pores. A cleaning procedure for the coral stone was standardized. -- AATA