Limestone Rock Information

Limestone rock is one of the most popular element when it comes to the field of architecture. Even though it is of great importance when it comes to architecture in North America and Europe, you get to see landmarks made from this rock type in other regions of the world as well. One of the best example of such landmark is the Pyramid of Giza in Egypt. Leaving aside its use in architecture and construction, other uses of limestone include making weather proof roofing, as an acid neutralizing agent, in cement production etc.

Limestone Rock Facts

Basically, limestone rock is a type of sedimentary rock which is mainly composed of mineral calcite and aragonite - which are nothing but crystal forms of calcium carbonate. This type of rock generally forms in clear, warm and shallow marine waters. Going by proper definition, any rock which has more than 50 percent of calcium carbonate in form of calcite qualifies as limestone rock. The remaining matter of this rock is made up of other materials, including small particles of feldspar, quartz, pyrite, clay minerals, etc.

Formation: The formation of limestone rock is one of the best examples of sedimentary rock formation - wherein the remains of various marine organisms as well as other debris which are drained in the water body accumulate as a sediment and eventually gets lithified into limestone. This, however, doesn't mean that limestone rock formation is restricted to water bodies. In caves, limestones are formed as a result of evaporation. When water seeping from the cave ceiling and walls evaporates through cracks in the cave, the calcium carbonate content in it is dropped on the cave floor. The sediment accumulates over the period and the results in formation of the rock. The entire process, which is a part of the rock cycle, takes thousand of years to complete.

Properties: Even though limestone rock is generally white in color, the impurities in it can give it different colors as well as patterns. The rock brown and red color of limestone is attributed to the presence of impurities of iron oxide in it, while black or gray color is attributed to the presence of carbon impurities in it. The texture of this rock type can range anywhere between fine to coarse. As in case of various other sedimentary rocks, even limestone rock is usually composed of grains - most of which are skeletal remains of marine organisms. Even though most of its varieties are granular, the chances of you coming across ones which are not granular cannot be ruled out. These non-granular limestone rocks (one of the best example of such limestone type is travertine) are formed as a result of chemical precipitation of calcite or aragonite.

Varieties: On the basis of its formation, appearance and composition, limestone rocks are categorized into various types or varieties. While chalk is a fine, white or light gray colored limestone rock which is formed as a result of deposition of calcareous shell remains of microscopic marine organisms at the floor of the water body, travertine is a limestone variety which forms as a result of evaporative precipitation, which results in formation of stalactites and stalagmites, in caves. Other popular varieties of limestone rock include coquina - which is mainly composed of broken shell debris, oolitic limestone - which is mainly composed of calcium carbonate oolites, fossiliferous limestone - which is composed of fossil remains which are obvious and abundant, etc.

Being partially soluble, this rock type has the tendency of forming various erosional landforms. In geology, these erosional landforms which contribute to limestone rock landscaping are known as karsts.