Dolomitic Limestone

There are various types of rocks found in nature, such as igneous, metamorphic, and sedimentary rocks. Their origin or their process of formation is the criteria that divides them into these categories.

Igneous rocks are formed from the lava of volcanoes. Metamorphic rocks, as the term suggests, are igneous or sedimentary rocks that undergo transformation over a span of time.

Sedimentary rocks are formed due to layers of sediments of various materials and deposits from water bodies. These sedimentary rocks contain many mineral and organic deposits. There have been examples of fossils being found in these rocks.

Limestone is a sedimentary rock, that mainly consists various forms of calcium carbonate, such as calcite or aragonite. Dolomite is also a sedimentary rock that consists mainly of magnesium calcium carbonate salts.

These rocks contains 10 to 50 percent of dolomite and more of calcite, which varies from around 50-90 percent. A rock is referred to as dolomitic limestone, only when the dolomite percentage is more than 10 percent and less than 50 percent.

Decomposition of this rock is a very complex process that is studied in chemistry and to an extent in geology. It requires higher temperatures for decomposition, wherein it first forms a salt of calcium carbonate and magnesium oxide, then it decomposes to calcium oxide and magnesium oxide. At each stage there is formation of carbon dioxide gas.

There are various uses of limestone that are known to many. However, if you are into agriculture, or even gardening for that matter, then you need to know about dolostone. It is one of the main ingredients of many fertilizers. The purpose behind including this is the presence of macro-nutrients, magnesium, and calcium.

These are usually present in soils, but when the soil is too acidic, and lime is used to adjust the pH, addition of these nutrients is necessary. Thus its fertilizer has it all, lime to maintain the pH at optimum levels, calcium, and magnesium.

Addition of this rock raises the pH of acidic soils, to a preferred range of 6 to 6.5, which is on the higher acidic pH side of the pH scale. The advantage of adding this particular ingredient is that, when the pH of the soil is adjusted by the lime, the nutrients become more readily available for absorption.

This range is also suitable for microbial growth in soil, to convert elemental nitrogen into forms that can be absorbed by the roots. It also improves the texture and quality of soil with respect to aeration and water absorption.

Many a time, dolostone is available in various forms, as an additional ingredient to your fertilizer. Studies have shown that the smaller or powdered form is more effective than the coarser particles.

Pelletized form is also available in the market, which are first crushed into a powder form as fine as flour, and then made into pellets for fertilizers, which dissolve due to moisture.

Certain types of limestones have a higher content of calcium. This is known as high calcium limestone. It is used in agriculture, but it also has an industrial application. It is also used as raw material in the precipitated calcium carbonate market (PCC), which is used to make good quality paper. It also finds an application in the sugar industry.

The products of these rocks are not that expensive and are therefore extensively used in agriculture.