In mineralogy and petrology, an aggregate is a mass of mineral crystals, mineraloid particles or rock particles.[1][2] Examples are dolomite, which is an aggregate of crystals of the mineral dolomite,[3] and rock gypsum, an aggregate of crystals of the mineral gypsum.[4] Lapis lazuli is a type of rock composed of an aggregate of crystals of many minerals including lazurite, pyrite, phlogopite, calcite, potassium feldspar, wollastonite and some sodalite group minerals.[5]