This paper provides a further investigation of the role of vein structures in the ease of mineral liberation by random masking simulation of breakage. A copper porphyry ore with vein-type mineralisation underwent different methods of sample preparation for liberation analysis. A selected core was cut into semicircular slabs and another core underwent crushing. The slabs and the crushed particles were analysed in the MLA and subjected to simulated breakage from which the liberation of sulphides was determined. The result was linked with the liberation measured from particles of the same ore that have undergone actual breakage. The analysis further provided an indication of the significant contribution of veins in liberation. This information points out to a proper approach of texture and liberation analyses, and the better use of textural data from core scale logging relevant to mineral processing.