What is Dolomite? - Definition, Structure & Uses

Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

Dolomite is a mineral that you may not have heard of, but it is still an important part of your life. Check out this lesson to learn about the structure, properties, and uses of this interesting natural resource.

More Than Just a Mineral

Rocks totally rock. You may think that they're just sitting there, looking boring, but rocks are what hold up mountains and contain the sea; they give us roads, airplanes, buildings, and even jewelry and art. In fact, each person in the United States will use an estimated one million pounds of rocks, minerals, and metals throughout their lifetime.

Dolomite is an important component on Earth, including in structures such as the Dolomite mountains
The Dolomites

Which brings us to a second point - rocks rock, but minerals rule. Minerals are what make up rocks, giving them different properties, shapes, and structures. And the specific mineral that's the focus of this lesson is a pretty great one as far as minerals go. It's called dolomite, and it's named for the French mineralogist Deodat de Dolomieu. You may hear 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.

The true dolomite mineral is a calcium magnesium carbonate and has the chemical formula CaMg(CO3)2. 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.

Dolostone, which has a number of uses, is rock that contains the mineral dolomite
dolostone

Structure

Dolomite cleaves, or breaks along smooth planes, in three different directions. On the Mohs hardness scale, which rates how difficult it is to scratch a mineral, dolomite comes in at 3.5 - 4. For reference, talc, which is very easy to scratch is at 1 on the scale, and diamonds, which are incredibly difficult to scratch, are at 10.

Dolomite is a double salt. This means that while it is composed of two salts (calcium and magnesium) it has a different structure than either of those individual salts. The calcium and magnesium salts exist in separate layers in the mineral, with carbonate layers in between them. What this looks like is a calcium layer, then a carbonate layer, then a magnesium layer, then another carbonate layer, and then a calcium layer, and so forth.

Dolomite may be colorless, white, pinkish, or slightly blue. The crystals of dolomite may be transparent, translucent (semitransparent), or completely opaque (not able to be seen through).

Uses of Dolomite

As dolostone, dolomite has an incredible number of uses. This is partly because dolomite is both abundant and occurs in large deposits that can be easily mined. In fact, dolomite (along with calcite and aragonite) makes up about 2% of the earth's crust.

Dolomite is widely used in construction materials, such as asphalt
image of a road

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