What Characteristics Does Limestone Have?

Color

• Limestone is mostly white or off-white in color, but can range to gray, brown and yellow as well. Gray and black streaks found in the material is staining caused by organic matter. Yellows and browns are mostly caused by iron oxide impurities present in the rock.

Texture

• Limestone ranges from a coarse material to very fine particles. Fossil fragments, pieces of old shells and other fossilized matter make up a large part of limestone. Sometimes these fossilized fragments can be easily seen with the naked eye. Other times, the material is so fine and crystallized that any fossilized remains cannot be identified.

Softness

• Limestone is soft and scratches easily. In the outdoors, wind, rain and atmospheric pollutants combine to weather limestone, dissolving it over long periods of time. The rock reacts easily with most common acids, such as vinegar or hydrochloric acid. When acid is applied, limestone effervesces, fizzing wildly. Acids occurring naturally in the environment cut through limestone as groundwater works its way through the rock. This process results in the caves and sinkholes of a Karst landscape.

Porosity

• Limestone is a porous material that is readily stained by a variety of substances. Oil and grease penetrate deeply into the material, while dyes and inks tend to stay closer to the point where they are introduced. Organic materials, such as leaves or bird droppings, mar the surface with reddish-brown irregularities. Some metals, such as iron and copper, leave stained surfaces with some penetration into the porous rock.

Limestone Uses

• Despite its softness and erosion over time, limestone is used as a base structural component and it is used to produce ornamental work as well. Its primary uses are in road construction, as a component in concrete and as a crushed material used in agricultural lime.