Equipment Explained | The Olive Oil SourceThis is not the case. Different equipment have different pros and cons, as you will see below, but the notion that stone mills are superior is mainly a marketing twist to sell olive oil. Stone Mills Stone rollers or wheels roll in circles on a slab of granite to grind the olives into a paste.grinding the olives machine,Olive oil extraction - WikipediaGrindstones, while ancient in design, are a suitable way to grind olives, because this method breaks up the drupe's pulp while only slightly touching the nut and the skin. This reduces the release of the oil oxidation enzymes present in these organs. In addition, in this extraction method, the introduction of water is minimal.