Rocks. Rock Products and Uses - Limestone.. The Manufacture and Uses of Lime.. What is Lime?. The name "lime" is used for both calcium oxide (quicklime),and calcium hydroxide (slaked lime).. How is Quicklime (Calcium Oxide) Made?. When limestone (calcium carbonate) is heated, at about 1000 °C it undergoes thermal decomposition. It loses carbon dioxide and turns into quicklime (calcium oxide).