Particulate chalcopyrite samples (78 ~ 98 mole per cent chalcopyrite, screen size fraction from 710 to 250 m) were prepared by crushing and sieving lump ore samples from 12 locations in the Mt Isa Mine. Measurements of thennoelectric power (which does not involve the passage of a current) were made using a packed bed that was compressed by loading with a weight and placed in a temperature gradienL Details of the apparatus are described.The effect of particle size was investigated by preparing 12 fractions, with mean particle sizes ranging from 605 to 2.2 m, from one of the ore samples. Values of thennoelectric power decreased with both increasing particle size and loading pressure; however it remained fairly constant for particle sizes above 80 m, when loading pressure exceeded 3.3 MPa.Measurements of the chalcopyrite samples gave an average value of -260 JlV/K (-248 ~ -268 V/K) for nine samples and about -290 V/K for three samples, showing that these samples were all n-type semi-eonductors.