Barite

Drilling Industry: The overwhelming majority of the barite that is mined is used by the petroleum industry as a weighting material in the formulation of drilling mud.  Barite increases the hydrostatic pressure of the drilling mud allowing it to compensate for high-pressure zones experienced during drilling.  The softness of the mineral also prevents it from damaging drilling tools during drilling and enables it to serve as a lubricant.  The American Petroleum Institute (API) has established specifications for the use of barite in drilling mud.
Medical Industry: An application where many people have heard of barite is within the medical field.  A high-purity form of barite is used in the gastrointestinal tract where its density prevents x-ray penetration, and thus is visible on an x-ray.  The outline of the gastrointestinal tract thus becomes visible allowing the determination of normal and abnormal anatomy.
Other Uses: Barite is also used in a wide variety of other applications including plastics, clutch pads, rubber mudflaps, mold release compounds, radiation shielding, television and computer monitors, sound-deadening material in automobiles, traffic cones, brake linings, paint and golf balls.