Cobblestones, with the light hand of sculptor Ivan Shadr, are associated with the weapons of the proletariat. During the revolutionary events of 1917, all Moscow sidewalks, including Red Square, were paved with such stones. Today’s heavy-duty diabase appeared on it only in 1930. In ancient times, this stone from the family of basalts was used by miners as a substitute for metal in making the striking part of a pick. Diamonds, corundum and topaz are the hardest of all minerals. No houses are built of diabase. The only known example is the summer residence of Count Vorontsov in Alupka.