Laboratory
Limestone
Limestone forms the most important hills in England: the Pennines, the Mendips and the Cotswolds.
Chalk, which is a type of limestone, forms the Chilterns and the North and South Downs.
It’s lucky that limestone is found close to so many of our big cities because of all rocks it’s the one we use most. Pure limestone is calcium carbonate and is made of the mineral calcite, but some limestones contain magnesium.
Here are just some of the many ways we use limestone.
Crushed rock – concrete is a mixture of aggregates, cement and water. Limestone is an ideal rock to use for concrete because it’s hard, easy to find, and it bonds (joins) well with cement. Crushed limestone is used in the construction of layers of roads. It can also be spread on fields by farmers to make the soil less acidic.
Building and ornamental stone – limestone is used for building in many parts of Britain because it’s soft enough to shape into rectangular blocks with a saw, and can be carved easily with a chisel. St Paul’s Cathedral and the Houses of Parliament are made of limestone.
Finely ground up limestone is used in toothpaste and in polishes. Powdered limestone is used in face powder to absorb moisture. Many cosmetics contain more of it than anything else. Many articles made from plastics use limestone powder as a sort of packing material, for example, car bumpers and paints. Limestone is used to give a white colouring to paints, plastics and rubber.
Chemistry – powdered limestone or lime is used to remove the gas sulphur dioxide, produced when power stations burn coal or oil.
Quicklime - limestone is made mostly from calcium carbonate. If you heat limestone strongly enough you produce a gas called carbon dioxide. The substance left behind is called calcium oxide, also known as Quicklime. It’s used to purify steel and other metals, in glassmaking, and to treat (clean) wastes from the textile and food industries.
Nutrient – all animals need calcium in their diet. Limestone is added to many animal feeds and also bread.
Lime – if limestone is heated it changes to lime and carbon dioxide. Lime has many uses in industry: for example, in making things as different as sugar or steel.
Cement works are normally located where both the main ingredients, limestone (80%) and clay (20%) can be found close by. At Quarryville, we quarry both and then grind them to a fine powder which must have the correct proportions of calcium, aluminium, silicon and iron.
If people stopped using limestone we’d go out of business – but giving its thousands of uses, that’s not likely to happen any time soon!