Barite or barytes (barium sulphate) is a mineral largely used (77% of it) as a weighting agent for drilling fluids in oil and gas exploration. It is an essential component and there is no substitute that has all of its properties.
A drilling fluid is used to aid the drilling of boreholes and barite is used as a weighting agent to increase the density of the fluid to help control pressure from the gas or oil reservoir. Its other properties of being relatively soft, inert and non-magnetic have benefits in terms of drill wear. 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.