Limited availability of representative sample material for mineralogical and metallurgical studies is a common problem. Samples are typically composites that contain mineralogical variation, which hinders mapping of ore variability. Understanding and characterizing ore variability is the most important part of the geometallurgical framework and is essential for optimization of production. Information about ore blocks' hardness, mineralogy, and metallurgical response guides planning and management of mining and processing. Standard grindability tests, like the Bond test, may require up to 10 kg of sample material and are rather time consuming. Here we present a rediscovery of an old comminution test method that is quick and requires only a small amount of sample material. Grindability tests were conducted with an Outotec Mergan mill and the results were compared with tests carried out with a conventional Bond ball mill. Based on the results, there is a linear correlation between the Mergan work index and the Bond work index. Mergan grinding tests enable prediction of the Bond work index quickly and using only about a five-kilogram sample. Furthermore, the ground sample material is available for analysis of chemical and mineral composition and for metallurgical testing.