What is limestone and how is it formed?
Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal, and fecal debris.
To make Portland cement—the most common type of cement—powdered limestone is heated in a rotary kiln. As a source of calcium, it joins with powdered clay to produce a product called clinker, which is then ground with a source of sulfate, like gypsum. It is mixed with water, sand and crushed rock to create concrete.
- Cement is made by heating powdered limestone with clay. Cement is an ingredient in mortar and concrete: mortar, used to join bricks together, is made by mixing cement with sand and water. concrete is made by mixing cement with sand, water and aggregate (crushed rock)
- Limestone is a sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO3). It often has variable amounts of silica in it, as well as varying amounts of clay, silt, and sand. Limestone rocks fall under the category of sedimentary rocks that are made from mineral calcite.
- Composition. Portland cement consists essentially of compounds of lime (calcium oxide, CaO) mixed with silica (silicon dioxide, SiO2) and alumina (aluminum oxide, Al2O3). The lime is obtained from a calcareous (lime-containing) raw material, and the other oxides are derived from an argillaceous (clayey) material.
Soil acidity is one of the factors that can influence plant growth and can seriously limit crop production. By spreading agricultural lime onto the paddock or soil, the calcium carbonate content of the limestone is capable of neutralising some of the acid in the soil.
- Marble is a metamorphic rock formed when limestone is exposed to high temperatures and pressures. Marble forms under such conditions because the calcite forming the limestone recrystallises forming a denser rock consisting of roughly equigranular calcite crystals.
- Lawn grasses tolerate a pH of between 5.5 and 7.5. It takes 20 to 50 pounds of ground limestone per 1,000 square feet to correct a mildly acidic lawn. Strongly acidic or heavy clay soil may need as much as 100 pounds. In small garden beds, you can estimate the amount of lime you need with the following information.
- Burnt and hydrated limes act fastest, although all three lower soil acidity, provide nutrients like magnesium and calcium, and encourage helpful bacteria. Because overly acidic soil isn't good for grass, lime is used to make it more alkaline.
It is the raw material for the manufacture of quicklime (calcium oxide), slaked lime (calcium hydroxide), cement and mortar. Pulverized limestone is used as a soil conditioner to neutralize acidic soils (agricultural lime). Is crushed for use as aggregate—the solid base for many roads as well as in asphalt concrete.
- LIMESTONE: A sedimentary rock, it is used mainly in the manufacture of Portland cement, the production of lime, manufacture of paper, petrochemicals, insecticides, linoleum, fiberglass, glass, carpet backing and as the coating on many types of chewing gum. SHALE: A sedimentary rock, well stratified in thin beds.
- Limestone is an organic, sedimentary rock. Limestone is formed in layers - called bedding planes. These bedding planes contain vertical cracks called joints. Joints and bedding planes make the rock permeable.
- In large parts of the United States there are extensive deposits of marine limestone of various ages from a few thousand to more than 350 million years old.
Updated: 3rd October 2019