This dataset contains scanning electron microscope (SEM) backscatter images of volcanic rock samples collected from deposits associated with the 1877 eruption of Cotopaxi Volcano, Ecuador. The samples represent a range of eruptive products, including airfall deposits, pyroclastic density current (PDC) deposits and volcanic bombs. The dataset comprises high-resolution SEM backscatter images acquired at ×50 and ×1000 magnifications to show the macro and micro-textures, crystal textures at all scales and mineral distributions. A supporting document containing sample information and SEM settings is included within the dataset archive. The data were collected, between August 2024 and January 2026, as part of the NERC-funded project NE/W008033/1 The explosivity of volcanic eruptions: Quantifying the critical role of permeability in magmas.