Under a Metal Sky - A Journey Through Minerals, Greed and WonderThe discovery of minerals beneath our feet has transformed our species. Ochre first prompted humans to express themselves in art; tin and copper helped instigate the Bronze Age and later the Industrial Revolution; silver kick started the engines of global trade. Each of these substances generated a leap forward in technology, each one opened the imagination a little further and each one brought with it a cache of unexpected dangers. Under A Metal Sky