Even in modern times we are fascinated by crystals – from the diamonds we use as a sacred symbol of partnership, to the plethora of ‘healing’ gems that can be found in a New Age gift shop. So we can only imagine how ancient people viewed these transparent rocks with hidden structure. Evidence of the esteem in which crystals were held can be found in a “remarkable set” of ‘crystal weapons’ found in the megalithic tombs of southwestern Spain. At the site of Valencina de la Concepcion, archaeologists have uncovered crystal arrowheads, an exquisite dagger blade, and cores used for...