Olivine basalt occurring three miles E.S.E. of Dergholm has been investigated by drilling and laboratory testing. Float and a single exposure are weathered, but fresh basalt occurs under an overburden of 5-20 feet (average 11.9 feet). Olivine phenocrysts and olivine-rich Xenoliths comprise 10-20% of the rock; siderite, dolomite and calcite, 5-15%; groundmass glass and segregated glass about 25%; iddingsite and other iron minerals, up to 15%; pyroxene and plagioclase phenocrysts, serpentinite, opal, and chalcedony are minor constituents; crystalline groundmass comprises the remainder. Twelve diamond drillholes have defined 312,000 cubic yards of fresh basalt below 144,000 cubic yards of moderately weathered basalt and clay. Los Angeles abrasion values range 16-21; Sulphate Soundness losses are 3.0 and 3.8, obtained from two samples. Limited petrographic data suggest that secondary clay and iron-oxide minerals in the fresh basalt are not present in sufficient quantity to have an adverse effect on the stability of paving surfaces. Further work is recommended before a satisfactory source of screenings can be assured.