Lapis Lazuli is a rock of multiple minerals. Lazurite makes up the blue color and also contains calcite (the white layers or lines) and pyrite (the gold colored spots). Lapis Lazuli may also contain Afghanite, Diopside, Dolomite, Hauynite (rare), Mica, Sodalite, Wollastonite (a white calcium mineral). True Lapis Lazuli must at least be 25% blue Lazurite.
Since the main source of Lapis is from Afghanistan it has become rarer and expensive due to the Taliban's activities. They aggressively take over mines and run illegal mines to fund terrorism.
Lapis has also been used as paint pigment (ultramarine). Vincent Van Gogh's 'The Starry Night' contains ultramarine tinted oil paint.