Igneous rock formed by the solidification of magma or lava (eg marble) - the size crystals that form depend on the rate of cooling (intrusive/extrusive)
Sedimentary rock formed by the compaction of layers of sediment over a long time (eg limestone and chalk) - may contain fossils and is not resistant to erosion
Metamorphic rock forms by heat and/or pressure of sedimentary rock (eg marble chalk or limestone)
Limestone, chalk and marble are all natural forms of calcium carbonate and exist in earth's crust
Demand for limestone is large so it must be quarried - there are economic, environment and social effects of quarrying it ( eg creation of jobs and destruction of habitat)
Commercial need for limestone: raw material for formation of glass, cement and concrete
Thermal decomposition of calcium carbonate is when it is heated and molecules are broken down into calcium oxide and carbon dioxide. Calcium hydroxide dissolves in water forming limewater - goes milky when carbon dioxide is present
Calcium oxide/hydroxide/carbonate used to neutralise soil acidity. Hydroxide is more popular
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