Dolomite gets its named from the French mineralogist Deodat de Dolomieu. True Dolomite mineral is a Calcium Magnesium Carbonate and has the chemical formula CaMg(CO3)2. It is thought to form when the Calcite (CaCO3) in carbonate mud or limestone is modified by magnesium-rich groundwater. The available magnesium facilitates the conversion of Calcite into Dolomite (CaMg(CO3)2). This chemical change is known as "dolomitization." Dolomitization can completely alter a limestone into a Dolomite, giving it unique technical properties that may set it apart from Calcites. There is also dolomitic limestone, which is limestone that contains dolomite, but it is not specifically the mineral itself. Additionally, Dolomite may also refer to rock that contains the mineral dolomite, but to be really clear here it's best to use the term dolostone to describe the dolomite-containing rock.
On the Mohs hardness scale, which rates how difficult it is to scratch a mineral, Calcite is a 3.0 while Dolomite is a 4.0. For reference, Soapstone, which is very easy to scratch is at 2.0 on the scale, and quartzite, which are incredibly difficult to scratch, are at 7.0. This means that Dolomites can be used on more demanding surfaces such as Kitchen Countertops, whereas calcitic stones such as Marbles would underperform.
As a simple carbonate, the Calcite molecule consists of a divalent calcium cation bound to a negatively charged (anionic) carbonate radical (I know, I know...you didn't come here for a Chemistry lesson. It will all makes sense. I promise). The weak ionic bonding between the calcium ions and the carbonate radical explains many of Calcite’s physical properties, including its relative softness of Mohs 3.0 and its tendency to stain when not properly sealed.
Dolomite on the other hand is a more complex and dense molecule (average density of Dolomite is 2.86 ton/m3) that has a closer atomic packing that strengthens the ionic bonds between the calcium and magnesium cations and the carbonate anions, making Dolomite much less susceptible than Calcite to the chemical action of acids and stains. (See...I told you!)
Dolomite is not combustible and therefore is considered a fire-resistant material. Because of its thermal conductivity, heat transfer is fairly rapid. Most stone is not considered a highly rated thermal insulator.
Dolomite crystals are typically colorless, white, gray or pink, but if iron impurities are present can be red, brown or even black. In massive form, Dolomite is typically buff, gray, or white. Under ordinary atmospheric conditions, Dolomites will endure for years without any change in color or durability.
Bacteria requires several things in order to thrive and grow: oxygen, water, sunlight, nutrients, and a substrate to form on. Dolomite slabs are double sealed before being polished and this treatment prevents bacteria growth. If an extra layer of protection is needed, dolomite may also be processed with bacteriostatic resin which utilizes a US EPA registered antimicrobial product.
While Calcite tends to be translucent, Dolomite tends to be opaque (not able to be seen through) unless it's cut with less then 3/4 ".
You may have heard the word Dolomite being used to describe a few different things so let's make sure we're on the same page about what we're actually talking about: Dolomite is a similar mineral to the mineral Calcite but at the same time, very different. In the following items we will try to show their similarities and differences.