Rocks

S13, E41: From the Stone Age, to the Space Age, we've built our world from rocks. Modern Marvels travels to America's horde of moon rocks located at NASA's Johnson Space Center. These rocks give us clues as to how the planets were formed, and how old the solar system is. Then it's off to see how marble and granite are extracted, cut, polished, and readied for use. We will learn how color, pattern, and surface finish are major considerations in the selection of any stone. We'll do some blasting at a sand and gravel pit, then see how sizes are graded. We'll mine iron ore, and watch it turned into steel. Finally we visit The Geysers in Northern California and see how they harness heat from rocks deep in the earth to create energy for nearly 850,000 homes.