A study of the composition, structure, and properties of Venusian rocks was carried out by Venera 13 and Venera 14. The main structural-morphological types of provinces of the Venus surface were chosen for the study. The chemical and mineralogical composition of the rock at the Venera 13 landing site shows that it belongs to a group of weakly differentiated melanocratic alkaline gabbroids; at the Venera 14 landing site, the rock is similar to oceanic tholeiitic basalts. A most interesting property of the surface rocks is the great number of the strata that were visible in panoramas of the landing sites. Measurements of their physical and mechanical properties show that Venusian rocks have friable, weakly cemented porous structures. Analysis of information from Venera 8, 9, 10, 13, and 14 led to the conclusion that the most likely global process responsible for the formation of the present rock is volcanic eruption. Moreover, due to the high gas content of basaltic melts, eruptions are of an explosive character leading to the formation of pyroclastic rocks. Summing up data obtained by Venera enbabled us to compare Venus with the earth, Mars, and the moon, to point out some regular global features in the evolution of these bodies, and to suggest some new problems for investigation.