What is Barite?

Barite is a mineral composed of barium sulfate (BaSO_۴). It receives its name from the Greek word “barys” which means “heavy.” This name is in response to barite’s high specific gravity of 4.5, which is exceptional for a nonmetallic mineral. The high specific gravity of barite makes it suitable for a wide range of industrial, medical, and .manufacturing uses. Barite also serves as the principal ore of barium.

Barite Occurrence

Barite often occurs as concretions and void-filling crystals in sediments and sedimentary rocks. It is especially common as concretions and vein fillings in limestone and dolostone. Where these carbonate rock units have been heavily weathered, large accumulations of barite are sometimes found at the soil-bedrock contact. Many of the commercial barite mines produce from these residual deposits.

Barite is also found as concretions in sand and sandstone. These concretions grow as barite crystallizes within the interstitial spaces between sand grains. Sometimes crystals of barite grow into interesting shapes within the sand. These structures are known as “barite roses” (see photo). They can be up to several inches in length and incorporate large numbers of sand grains. Occasionally barite is so abundant in a sandstone that it serves as the “cement” for the rock.

Physical Properties of Barite

Barite is generally easy to identify. It is one of just a few nonmetallic minerals with a specific gravity of four or higher. Combine that with its low Mohs hardness(۲.۵ to 3.5) and its three directions of right-angle cleavage, and the mineral can usually be reliably identified with just three observations.

In the classroom, students often have difficulty identifying specimens of massive barite with fine-grained crystals. They look at the specimen, see the sugary appearance, correctly attribute it to cleavage, and apply a drop of dilute hydrochloric acid. The mineral effervesces and they think that they have calcite or a piece of marble. The problem is that the effervescence is caused by contamination. The students tested the hardness of the barite with a piece of calcite from their hardness kit. Or the specimen of barite can naturally contain calcite. However, any student who tests the specific gravity will discover that calcite or marble are incorrect identifications.

Barite is also a good mineral to use when teaching about specific gravity. Give students several white mineral specimens that are about the same size (we suggest calcite, quartz, barite, talc, gypsum). Students should be able to easily identify barite using the “heft test” (placing Specimen “A” in their right hand and Specimen “B” in their left hand and “hefting” the specimens to determine which one is heaviest). Students in third or fourth grade are capable of using the heft test to identify barite.