Flint. It is the name given in geology to a type of very hard rock, which when fractured forms very sharp edges. It is made up mostly of silica and small amounts of water and alumina. A variety of quartz that is compact and translucent at the edges. When it rubs against other rocks, it produces sparks. Name of two towns in Argentina (one in the Province of San Juan and the other in the Province of Entre Ríos).