1. n. 
A laboratory test to evaluate drilling-grade weighting material for potential abrasiveness. The test measures weight loss of a specially shaped, stainless steel mixer blade after 20 min at 11,000 rpm running in a laboratory-prepared mud sample. Abrasiveness is quantified by the rate of weight loss, reported in units of mg/min.
Mineral hardness, particle size, and shape are the main parameters that affect abrasiveness of weighting materials. Some crystalline forms of hematite grind to a higher percentage of large particles than do other forms and are therefore more abrasive. Hematites are harder than barites, grind courser, and are more abrasive. Thus, a hematite that is proposed as a weighting material for mud is typically a candidate for abrasion testing.