Lapis lazuli (sometimes abbreviated to lapis) is a relatively rare, semi-precious stone that has been prized since antiquity for its intense blue color.Lapis lazuli has been mined in the Badakhshan province of Afghanistan for over 6,000 years, and trade in the stone is ancient enough for lapis jewelry to have been found at Predynastic Egyptian sites, and lapis beads at neolithic burials in Mehrgarh, the Caucasus, and even as far from Afghanistan as Mauritania.Lapis lazuli is a rock, not a mineral: whereas a mineral has only one constituent, lapis lazuli is formed from more than one mineral.The main component of lapis lazuli is lazurite (25% to 40%), a feldspathoid silicate mineral composed of sodium, aluminium, silicon, oxygen, sulfur, and chloride. Its formula is (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2. Most lapis lazuli also contains calcite (white), sodalite (blue), and pyrite (metallic yellow). Other possible constituents are augite, diopside, enstatite, mica, hauynite, hornblende, and nosean. Some contain trace amounts of the sulfur rich lollingite variety geyerite.Lapis takes an excellent polish and can be made into jewelry, carvings, boxes, mosaics, ornaments, and vases. In architecture it has been used for cladding the walls and columns of palaces and churches.