Stone is developed when one or more minerals coalesce into a solid form. There are 3 main categories of natural stone: sedimentary, metamorphic, and igneous. Sedimentary stone are formed by mineral deposits on the ocean floor, or other bodies of surface water, that accumulate to create rock beds then bond together through pressure and heat. Limestone and travertine are examples of sedimentary stone. Metamorphic stone are stones that have changed (morphed) through heat, pressure and mineral deposits into another type of stone. Examples are marble, quartzite, slate, and soapstone. Igneous stone are formed by mineral liquids and gases penetrating volcanic magma before it cools and solidifies. Granite is igneous stone.