Sand, salt, iron, copper, oil and lithium are the stars of Ed Conway’s book, Material World. He tells Tom Sutcliffe how they built our world, from the Dark Ages to the present day. And how much the battle to secure them will shape our geopolitical future. The science writer Aarathi Prasad focuses on one of the world’s strongest biological materials ever known – Silk. In her latest book she explores the ancient origins of silk, its global reach, and how it continues to inspire new technologies – from pharmaceuticals to holograms. And materials and how different civilisations use them are at the heart of the British Museum’s exhibition, Luxury and Power: Persia to Greece (until 13th August). The curator, Jamie Fraser, highlights the perceived excesses of the Persian empire – with its abundance of gold, finely crafted pottery and frankincense – in direct contrast to the plainer tastes of their Greek victors. Producer: Katy Hickman