Lapis lazuli is a vividly blue rock, sometimes with streaks of gold, that has been known for millennia for its eye-popping colour and use as a semi-precious gemstone. It gets its colour from the ...

The blue flecks of lazurite came with microscopic bits of a clear mineral called phlogopite, another ingredient in lapis lazuli. It’s rich in iron and magnesium, and it’s possible to trace the ...