Barite - BaSO4.

Barite is a mineral that comprises barium sulfate (BaSO₄). It is usually colorless or milky white, but can be almost any color, depending on the impurities trapped in the crystals during their formation. Barite is relatively soft, measuring measures only 3 to 3.5 on the Moh's scale of hardness. Despite its softness, it is unusually heavy for a nonmetallic mineral. The high density is responsible for its value in many applications. Barite is chemically inert and insoluble. The most important commercial barite deposits are found in bedded sedimentary rocks. These types of deposits are mined in the United States in Arkansas and Nevada. Barite is mined in about 20 countries worldwide; China is the largest producer. The United States produces about one-fourth of its annual requirements. Nearly 98% of the barite used in the United States is as a weighting agent in oil- and gas-well drilling fluids. Because it significantly reduces X-rays (looks opaque on X-ray film), barium is used in medicine to diagnose gastrointestinal problems.

Name

Barite (spelled baryte in British publications) was named from the Greek word baros which means weighty, a reference to its unusually high specific gravity. (Specific gravity is a mineralogist's measure of the density of a mineral; this is done by comparing the weight of the mineral to the weight of an equal volume of water.)

Sources

Most barite is mined from layers of sedimentary rock which formed when barite precipitated onto the bottom of the ocean. Some smaller mines utilize barite from veins, which formed when barium sulfate was precipitated from hot subterranean waters. In some cases, barite is a by-product of mining lead, zinc, silver, or other metal ores.

There are nine barite mines in the United States; in Nevada, Georgia, Tennessee, and Missouri. China produces nearly ten times as much barite as the U.S., and India also produces more. About 40 other countries are also producers.

Many barite deposits are known worldwide, but some are uneconomic because barite can be mined more cheaply in China.

Uses

By far, the principal use for barite is as a "weighting agent" in oil and natural gas drilling. In this process, barite is crushed and mixed with water and other materials. It is then pumped into the drill hole. The weight of this mixture counteracts the force of the oil and gas when it is released from the ground. This allows the oil and gas rig operators to prevent the explosive release of the oil and gas from the ground. Currently, the majority of barite consumption in the United States is for this drilling application. However, the consumption in drilling "mud" fluctuates from year to year, as it is dependent on the amount of exploration drilling for oil and gas, which in turn depends on oil and gas prices.

Beyond this, barite is used as an additive to paints, enamels, and plastics, in the production of so-called "lead" crystal or "leaded" glassglass, stops radiation from computer monitors and television tubes, and as the source of barium chemicals.

Barite has the unique ability to strongly absorb X-rays and gamma rays. Consequently, it is used in medical science for special X-ray tests on the intestines and colon. It is also mixed with cement to make special containers used to store radioactive materials. A more recent application of barite is in the production of brake pads and clutches for cars and trucks.

Substitutes and Alternative Sources

Possible substitutes for barite, especially in the oil drilling industry, include other similar minerals, such as celestite (strontium sulfate, SrSO₄) and iron ore. A German company is producing synthetic iron ore (hematite) which is proving a good substitute for barite. However, these alternatives have yet to be widely used in the oil industry, and barite continues to be the preferred commodity for this application as long as barite production remains strong.