While limestone may seem like nothing more than a plain old rock, this mineral is actually quite an interesting one. Students who hold an interest in geology can learn a lot about this rock, uncovering an assortment of interesting facts and discovering just what makes this rock different from others.
Limestone, by definition, is a rock containing at least 50 percent calcium carbonate, or CaCO3. Because limestone is a sedimentary rock, the other elements that make up the rock are determined by the place where the limestone was formed. These other limestone-creating elements can include clay, pyrite, quartz and feldspar.
Limestone most commonly develops in wet areas when objects settle in the water, creating sediment and, ultimately, sedimentary rock. The primary chemical make-up of limestone is CaCO3. Because limestone originates in wet areas, along with other minerals, it can also include algal, shells and fecal matter from water animals.
Stalactites and stalagmites
The stalactites and stalagmites that garner so much attention in caves and caverns are products of limestone development. These structures that hang down from cave ceilings or stick up from cave floors are formed when water evaporates, leaving limestone in its wake. This process takes tens of thousands of years.
When completely pure, limestone is white, but because this mineral can be composed of an assortment of different minerals or other elements, it rarely remains this pale hue. The colour of limestone is determined largely by what elements combine with the calcium carbonate to make the rock, allowing this stone to be nearly any colour in the rainbow.
This mineral is commonly crushed and added to construction materials. It is also often used as an additive to thicken paint. When roof shingles have texture, this texture is often the result of crushed limestone added to the tar that covers the tiles. Surprisingly enough, this mineral is also often added to animal feed because some animals, such as chickens, benefit from the addition of limestone to their diets.