In this thesis a quantitative and qualitative analysis of multicoloured Košna conglomerates has been conducted. These conglomerates are found in the middle part of the Velebit Mt., in the Brušane area, along the “Košna voda” creek. The average particle size and their percentage in particular categories of the Udden-Wentworth classification were determined, and the percentage of matrix content was estimated. Particle and matrix lithology were determined using a petrographic microscope, while the present opaque minerals were identified using an ore microscope. Sandstone samples are classified as lithic arenites, subarkoses and feldspathic arenites. Beside sandstones, the conglomerates consist of limestone, chert and quartz pebbles. X-ray diffraction analysis showed that the red colour of conglomerate matrix is caused by hematite. Based on the conducted analysis and field observations, the Košna conglomerates are defined as Middle Permian petromict clast-supported and matrix-supported conglomerates, locally breccia-conglomerates. The material very likely originated from the uplifted Hercynian Mountains and was deposited in a marine environment.