A brief description of ten core plug samples collected from borehole GGC01 (Glasgow, United Kingdom) is provided, as well as for twelve 15-50 g cuttings samples from 1m intervals within borehole GGA08. Samples were also collected from borehole GGA02 but not used for further analyses. Data comprise results from geomechanical tests, permeability and porosity measurements, and X-Ray Diffraction analyses performed on drillcore samples of sandstones, siltstones, mudstones and coals from eleven depth intervals within the GGC01 borehole. Geomechanical data include triaxial compressional strength, tensile strength, and frictional strength. Frictional strength data was also collected for cuttings samples of sandstones, siltstones, mudstones and coals from the GGA08 borehole. In total twenty-three tensile strength tests were performed on ten sampled intervals, and seven porosity measurements pre-and post-failure were taken. Nine triaxial compressive strength tests and twenty-one frictional strength tests were performed, with permeability measured both before and after failure or shear respectively. From compressive strength tests we also determined the Young’s modulus and Poisson’s ratio. Samples and data are derived from the UK Geoenergy Observatories Programme funded by the UKRI Natural Environment Research Council and delivered by the British Geological Survey.

UKGEOS and Core Sample Analysis. Geomechanical testing was performed to determine triaxial compressional strength, tensile strength, frictional strength and permeability of sandstones, siltstones, mudstones and coals from eleven depth intervals within the GGC01 borehole, UK Geoenergy Observatories (UKGEOS), Glasgow, United Kingdom. Frictional strength tests were also performed on cuttings samples of sandstones, siltstones, mudstones and coals from the GGA08 borehole, Glasgow, United Kingdom. In total twenty-three tensile strength tests were performed on ten sampled intervals, and seven porosity measurements pre-and post-failure were taken. Nine triaxial compressive strength tests and twenty-one frictional strength tests were performed, with permeability measured both before and after failure or shear respectively. From compressive strength tests we also determined the Young’s modulus and Poisson’s ratio. Results of X-Ray Diffraction are also included in the dataset.