The word druse refers to an aggregate mass of small crystals. These crystal intergrowths or clusters can be formed by many different minerals. Druses typically form in open space or cavities in rocks beneath the earth's surface. The mineral species and shapes of crystals formed are dependent on fluid composition. Crystal size is a function of fluid temperature and pressure. Druse accumulations were druses of garnet, calcite, pyrite, hematite (specularite), azurite, quartz, psilomalene, chrysocolla, siderite, fluorite and sphalerite. The list of possible minerals which form druses could go on and on, with even natural forms of house-hold compounds such as salts and sugars on the list.