Agate, quartz, flint, jasper? - this is not a complete list of silica minerals. They decorate palaces and metro stations, they are equipped with accurate devices. At first, a person mined them in the ground, then learned to grow them in a laboratory. In extreme conditions, unusual silicas are synthesized - kitite, coesite, stishovite. How does this happen? What are silicas for? Why do they attract the attention of scientists? How are silicas used in modern science and technology? All this is described in the book.