What is limestone made of

Limestones - properties, use and care

Calcite, dolomite, marble or calcium carbonate - what is limestone made of?

Limestone is a sedimentary rock and is one of the rocks that are mainly composed of minerals such as calcite, dolomite and aragonite. Most limestones contain petrified debris, shell fragments, and other small fossils that are visible to the human eye upon closer inspection of the stone surface. However, some types of limestone are made up of extremely fine grains that are nothing more than fragments of marine organisms such as foraminifera or corals. Other grains that limestone includes are calcite, peloids, Jurassic limestone, calcium carbonate, ooids, and certain masonry stones. Limestone makes up almost ten percent of the total amount of sedimentary rocks on earth. Karst landscapes arise from the solubility of limestone in weakly acidic solutions and water.

What are the properties of limestone?

Limestone is usually gray in color, but it can also be brown, yellow, or white. It is a soft stone and can therefore be easily scratched. It tends to bubble up in any common acid solution. The porosity and texture of limestone differs from that of Coquina, a matrix of calcite shells, and that of oolitic limestones with fine structures. During major geological events, limestone deposits undergo a metamorphosis, during which limestone recrystallizes into marble. Limestone can be massive, granular, clastic, or crystalline, depending on the method of formation. In addition to these properties, some of the small cavities made of limestone can also be coated with crystals of dolomite, calcite or quartz. When wet, calcite crystals enable the formation of mineral coatings that cement the rock grains or fill the fractures.

In which areas are these rocks used?

Limestone is often used in the following areas:

  • Architectural application for walls, veneer and moldings
  • Soil improver
  • Raw material for the production of mortar, cement, slaked lime and quicklime
  • Supplement to calcium levels in forage
  • In glass production
  • Building material for terrace slabs and step plates
  • Pigment in tiles, paper, plastics, toothpaste and other materials

Can limestone be used for kitchen countertops?

Yes, but for some kitchens, rocks containing calcium carbonate are not always a good and sustainable choice. Limestone is very porous compared to other stones like marble, quartz and granite. A porous stone absorbs liquids and food, which can cause etching and staining. While the stone can be used for kitchen countertops, it requires far more care and maintenance than other options. Often times, limestone is successfully incorporated into kitchen design as an accent, but many homeowners are opting for a more durable stone for their main kitchen countertop. Limestone reacts with all acids, including citrus fruits like limes and lemons, vinegar, soda, coffee or wine. Spilled material should be washed off immediately to avoid staining and etching. Regular sealing and proper cleaning significantly reduce the risk of discoloration. Limestone is also one of the softer rocks that are prone to scratches. You cannot cut directly on the surface of the stone and you will need to be careful when dropping heavy objects on the surface and edges of the countertop. Cutting boards, coasters, and placemats are recommended to reduce scratches and cracks. The good news is that limestone is easy to repair. The stone can be sanded, polished, and resealed, essentially returning the stone to its original state.

Do limestone slabs need to be sealed?

Yes. Limestone is extremely porous, so it is important to seal the stone to avoid etching and staining. Most limestone countertops are sealed when they are installed, but need to be resealed about once a year. Seals can wear unevenly over time, so placemats and coasters are also recommended on sealed limestone. Regular cleaning and quick wiping of spilled liquids will extend the life of a sealant and the worktop.

How should I clean limestone slabs?

Limestone (sealed or unsealed) should only be cleaned with products with a neutral pH. Acid cleaners can cause burns, and abrasive cleaners can scratch the surface of the stone. You can regularly clean limestone with a mild dishwashing detergent and a mixture of warm water (about one teaspoon of soap per liter of water):

  1. Gently wipe the counters with the soap mixture and a soft cloth.
  2. Never use coarse scouring pads - just soak them in warm water and remove any soap residue.
  3. Thoroughly dry the stone with a microfiber cloth or a soft towel.

You can use mild detergents, but make sure they are suitable for finishing limestone, are non-acidic, and do not contain vinegar, ammonia, or any other high pH substance. Don't use stiff bristle brushes or steel wool on limestone unless you plan on resealing.

What is honed limestone?

Cut stones are designed flat so that there are no burrs or reflections. The appearance is a natural chalky look. Honed limestone is unpolished, so the finish has a flat, matte look with little to no sheen. Polished stones show fewer scratches than polished surfaces.