Dolomitic limestone is limestone that has been replaced with 10-50 percent dolomite, and 50-90 percent calcite. During its natural formation, the dolomite forms within the limestone, although scientists have been unable to identify or explain the exact mechanism that makes this possible. Limestone that naturally forms with more than 10 percent, but less than 50 percent dolomite, is considered dolomitic limestone. It was once referred to as magnesian limestone in the United States Geological Survey publications, but is now known as dolostone, dolomite rock, dolomite limestone, or dolomitic limestone. Dolomite is a mineral which contains large amounts of calcium and magnesium, which makes it ideal for fertilizer for nutrient deficient soil.

In addition to working as a fertilizer, dolomitic limestone is also useful for soils that are too acidic, or have an abnormally high pH level. Adding dolostone for the purpose of lowering the soil’s pH level is known as “liming.” Dolomite stone being sold as liming material typically contains a minimum of 30 percent magnesium.

It takes approximately one pound of dolomitic limestone per 20 square feet (1.85 square meters) of soil to lower the pH level. Sandy and well-drained soils may require even less, while clay soils often need more. It may take several weeks before a change in pH is observed, but it should not be over-applied. Too much dolomite in the soil can cause excess magnesium, which will change the soil structure to its detriment.

Dolomitic limestone has also been used in the container production of ornamental plants to balance the pH of their soil, and serve as a nutritional source of magnesium and calcium. Five to ten pounds (2.27 to 4.54 kg) of the substance is generally added to each cubic yard of growing media, including peat moss and pine bark, and then added to the plant containers. Application may include pelletized or finely ground dolomite stone, although a study conducted by the Auburn University’s College of Agriculture in the United States has shown that the ground version is more effective for this purpose.

Dolomitic limestone is naturally occurring, and is mined in the same areas as dolomite and limestone individually. The stones that are not used for agricultural purposes are often crushed down and used as filler in the manufacturing of pavement and concrete. Dolomitic limestones are found in many different places, including Indiana and Mississippi in the United States, and many areas of India.

In appearance, dolomitic limestone is slightly crystalline and is found in a wide variety of colors and textures. Pure dolomite is white to light pink in color, but dolomitic limestone may be any shade from white to dark gray. In most cases, it has a greater variety of texture than other types of limestone, and is greater in strength.