Six materials have shaped modern civilization

When it comes to examining the roots of the modern world, a new book takes an elemental approach. Ed Conway's "Material World: The Six Raw Materials That Shape Modern Civilization" (Knopf) looks at the influence of the elements iron, copper and lithium — along with salt, oil and sand. "Without them, normal life as we know it would disintegrate," writes Conway. How so? Sand is invaluable in the construction of the world's buildings, bridges or roads. But it's also vital to the production of glass and silicon chips. But even as the "most common" substance in the earth's crust," there's…