This paper describes the role of vein structures to better understand and interpret the origin of mineral liberation based on random masking simulation. An HQ half core from a copper porphyry deposit was selected and was cut into semicircular slabs of 1 cm thickness. Selected slabs were polished for MLA analysis. Classified MLA images were then subjected to image processing to identify and separate the veins from the disseminated grains. Random masking was applied on the images to simulate breakage and generate progeny particles from which liberation of sulphides was determined. Results of the simulation provided an indication of the contribution of veins in the liberation of minerals at coarser size and the increased degree of liberation. The work in this paper also suggests cutting drill cores and using slabs for texture analysis prpvides more intact textural features of the ore both at micro and mesoscale. Particularly, if veins occur to some extent, cutting the drill core into slabs is more suitable to preserve this structure providing a better understanding of the origin of mineral liberation. (C) 2016 Elsevier Ltd. All rights reserved.