tartrates, the general term used by winemakers to describe the harmless crystalline deposits that separate from wines during fermentation and ageing. In English the substances are also called argols, in French tartres and in German Weinsteine (literally, ‘wine stones’). The principal component of this deposit is potassium acid tartrate, the potassium salt of tartaric acid, which has therefore given rise to the name. Small amounts of pulp debris, dead yeast cells, precipitated phenolic materials such as tannins and pigmented tannins, and traces of other materials make up the impurities contaminating the potassium acid tartrate (see sediment).