A large 457.7-gram specimen of breccia from the massive Popgai crater in northern Siberia. Note the variety of colors, sizes, shapes and textures within a single mass—the result of a major meteorite impact which threw millions of tons of rock into the air. As fragments fell back to earth, rocks from different strata were mixed together. Millions of years of heat and pressure compressed those assorted pieces into a solid mass known as an impact breccia. Photograph by Geoffrey Notkin © Aerolite Meteorites.