Millstone in the context of "Molar (tooth)"

Grinding wheels are wheels that contain abrasive compounds for grinding and abrasive machining operations. Such wheels are also used in grinding machines.

The wheels are generally made with composite material. This consists of coarse-particle aggregate pressed and bonded together by a cementing matrix (called the bond in grinding wheel terminology) to form a solid, circular shape. Various profiles and cross sections are available depending on the intended usage for the wheel. They may also be made from a solid steel or aluminium disc with particles bonded to the surface. Today most grinding wheels are artificial composites made with artificial aggregates, but the history of grinding wheels began with natural composite stones, such as those used for millstones.

Gritstone or grit is a hard, coarse-grained, siliceous sandstone. This term is especially applied to such sandstones that are quarried for building material. British gritstone was used for millstones to mill flour, to grind wood into pulp for paper and for grindstones to sharpen blades. "Grit" is often applied to sandstones composed of angular sand grains. It may commonly contain small pebbles.

"Millstone Grit" is an informal term for a succession of gritstones which are to be found in the Pennines (including the Peak District) of northern England. These sediments were laid down in the late (upper) Paleozoic era, in the Carboniferous period, in deltaic conditions. The Millstone Grit Group is a formal stratigraphic term for this sequence of rocks.

A ruff is an item of clothing popular in Western, Central and Northern Europe, as well as Spanish America, from the mid-16th century to the mid-17th century. A round and flat variation is often called a millstone collar after its resemblance to millstones for grinding grain. Ruffs are still worn by Lutheran clergy in Denmark and Germany.

Stoneground flour is whole grain flour produced by the traditional process of grinding grain between two millstones. This is in contrast to mass-produced flours which are generally produced using rollers. The process leaves the wheatgerm more intact than roller processes for producing wholemeal flour, the larger pieces of bran and other components of the grain cause it to have a coarser texture but greater flavour. This affects its ability to rise, however it can produce a more satisfying texture for some baked products. The inclusion of more bran and intact wheatgerm in the flour means that it is often credited with significant health benefits.

In the US, flour only has to "pass between stones" once during its manufacture to be regarded as stoneground, and it has been claimed that a significant proportion of flour sold as stoneground in the US has not been processed in this way, being ordinary roller-ground wholemeal.