1. n. 
A type of drilling-fluid solid having a lower density than the barite or hematite that is used to weight up a drilling fluid, including drill solids plus the added bentonite clay. The mud engineer calculates the concentration of these and other types of solids on the basis of mud weight, retort analysis, chloride titrations and other information. Solids are reported as lbm/bbl or vol.%. Water is 1.0, barite 4.20, and hematite 5.505 g/cm3. Low-gravity solids are normally assumed to have a density of 2.60 g/cm3..