Editing Millstone (section)

== Different techniques: grinding, crushing, milling ==
The preparation of vegetable products ([[Root|roots]], [[Tuber|tubers]], [[Almond|almonds]], [[Leaf|leaves]], etc.), animal products ([[Bone marrow|marrow]], [[Tendon|tendons]], etc.), or mineral products ([[ochre]]) by grinding or milling, for consumption or technical use, has existed for several dozen millennia. Unlike crushing, in which a hard envelope such as a shell or bone is broken open to recover its contents, in this case, the aim is to reduce a much softer material to a [[powder]] or paste.

Depending on the place and time, millstones were used for "dry" grinding: in the manufacture of [[flour]], [[sugar]], or [[Spice|spices]], but also for the preparation of [[kaolinite]], [[cement]], [[phosphate]], [[Limestone|lime]], [[Enamelled glass|enamel]], [[fertilizer]], and other [[Mineral|minerals]]. The milling operation can also be carried out "wet", as in the case of [[Durum|durum wheat]] [[semolina]], [[Nixtamalization|nixtamal]], or the grinding of [[Mustard seed|mustard seeds]]. During preparation, some raw materials produce a naturally fluid paste, as in [[olive]] crushing or [[Cocoa bean|cocoa]] grinding.

In his typology of percussion, [[André Leroi-Gourhan]] defines several families of gestures, three of which are essential for the preparation of raw materials:

# ''Crushing gestures'' involve vertical [[Impulse (physics)|percussion]] using a heavy, elongated object in the manner of the African pestle. This gesture is also used by the [[trip hammer]] to make [[Pulp (paper)|paper pulp]], or in [[forging]];
# ''Milling gestures'', using percussion, which are performed in a circular, disordered, or back-and-forth motion on a millstone;
# ''Grinding gestures'', in which the movements are roughly circular and occasionally vertical, thus combining a thrown percussion and a percussion posed, are qualified here as diffuse. This is the case with the contemporary [[Mortar and pestle|mortar-pestle]] system.
<gallery mode="packed-overlay" heights="200" widths="250">
File:Pounding_millet_MS0818.jpg|Pilon: ''Vertical percussive '''crushing'''''
File:RICE_POLISHING_BY_FOOT_POWER.jpg|'''''Crushing''' by hammering''
File:Aboriginal_grinding_stones.jpg|Monolithic millstone with knurled wheel: ''percussive '''milling''' with uncoordinated movements''
File:P1010979mod.jpg|Peruvian Stone [[Batan (stone)|Batán]] (sandstone): ''Percussive '''milling'''''
File:Black_peppercorns_with_mortar_and_pestle.jpg|Mortar and pestle: '''''Grinding''' by diffused percussive impact and diffused percussive application''
</gallery>