Test materials included oil shale dusts varying in richness (Fischer assay yields) and particle size. These samples were either freshly prepared or obtained from dist deposits in the colony oil shale mine. Analyses carried out included Fischer assay and determination of total volatile hydrocarbons, organic carbon and pyritic sulfur. Data obtained at the Denver Research Institute on laboratory dust ignition and explosivity properties and on the tendency for spontaneous ignition, and the values were correlated with the chemical properties. Explosivity properties increase as the organic content of the oil shale dust increases and as the particle size decreases. However, oil shale dusts were shown to be much less explosive than coal dusts.