The invention provides a method of manufacturing a solid phase barite containing material for use in a wellbore. The method includes the steps of providing the barite containing material having relatively small particles with a particle size distribution of at least 50vol% particles having a diameter in the range of 1µm to 10µm and at least 90vol% particles having a diameter in the range of 4µm to 20µm; and contacting the barite containing material with a liquid in order to form relatively large particles having a particle size distribution with at least 90vol% of the particles having a diameter of at least 30µm. There is also described a method of treating a wellbore with a fluid including the barite containing material.
