Integrated petrological observation of samples from the Lower Jurassic of the Llanbedr (Mochras Farm) borehole, Wales. The data include quartz grain size and percentages of the major detrital minerals present in each sample. Analyses were carried out using automated mineralogy (QEMSCAN) technology. QEMSCAN® (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) allows mapping of grains from elemental compositions, including attributes such as texture, shape, size and constituent mineral phases. Data relate to the Llanbedr (Mochras Farm) Borehole drilled in 1967-1969 near the village of Llanbedr, NW Wales, SH 5533 2594. The aim for generating these data was to provide mineralogical context for paleoenvironmental proxy interpretations from the Llanbedr (Mochras Farm) core. Samples from the UK National Geological Repository range from SSK Publication in press, Jiang et al. (2026) Laurasian Seaway history during the Early Jurassic from quantitative mineralogy and detrital zircon dating. Paleoceanography and Paleoclimatology.