Early in 1909 a small quantity of fine sand was brought to the writer from a big Chinese-owned mine at Rotan Dahan, in the district of Kinta, the leading tin-producing district of Perak and, indeed, of any of the Federated States. The sand was a concentrate, and had been obtained in the final washing of the rough tin-ore concentrates, whereby the heavier impurities, generally referred to locally as ‘amang’, are separated from the cassiterite. In this case, however, the Chinese miner found that there was a reddish mineral present which he could not separate from the cassiterite. This proved to be native copper, and the mode of occurrence is of sufficient interest to watTant a brief description of this and other samples of ore from the same mine and an adjoining mine working on the same deposit.