|Abstract||Hardness, defined as resistance to surface deformation, is intrinsic to all materials including sedimentary rocks. The variables controlling sedimentary rock hardness are not completely understood. By understanding these factors, we may better understand related rock strength. Rock strength, defined as a rock’s resistance to brittle failure under loading, is important to many industries such as mining, civil engineering, and petroleum exploration. Rock strength is typically quantified by triaxial load cell tests, which are expensive, time consuming, and require substantial investment in laboratory setup. To circumvent this, other devices have been employed to determine rock strength. For example, the Proceq Equotip Bambino micro-rebound hammer (Bambino) has been used for decades to test the hardness of manmade materials, and to determine strength. Geologic studies empirically correlate Bambino-derived hardness (called Leeb hardness) and uniaxial compressive strength (UCS). However, significant scatter in the data suggest that certain intrinsic (e.g., density) or extrinsic factors (e.g., sample volume) need to be considered for a better correlation. In this study, I examined relations between Leeb hardness and UCS values, accounting for properties such as: lithology, bulk mineralogy, water loss, volume, density, and effective porosity. Intrinsic properties such as bulk mineralogy, density, effective porosity, and water content correlate with Leeb hardness. Also, sample UCS is related to its density, effective porosity, and mechanical hardness. Ultimately, this study validates previous studies and sheds insight on the controlling properties of a rock’s hardness and strength.