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grapegrowing minerality of the wine and the specific vineyard geology would seem to be entirely plausible—at first glance. In fact, the latest trend is to further embellish the term with a reference to some specific mineral (as in a quartz, gypsum or graphite minerality) or rock (as in a chalky, slaty or granite minerality), as though specific geological materials conferred particular kinds of mineral tastes. Clearly the popular wine press finds the whole idea of minerality not only useful, but simple and attractive. Nutrient minerals versus geological minerals What is wrong with the view that minerality is literally the taste of vineyard minerals? For a start, there seems to be confusion about the very word mineral. Directly relating minerals in wine with those in the vineyard soils implies that they are the same things. However, although ultimately linked, they are not the same. When we talk about minerals in foodstuffs such as wine, we usually mean single elements. They are mostly inorganic metals such as calcium, potassium and zinc. These are minerals in the nutrient sense. It is the same in plants. If they are in solution, as in vine sap, grape juice and wine, these nutrient minerals are in ionic form as cations—e.g. K+, Ca++, and Mg++. But minerals in the vineyard bedrock, stones, and the physical framework of the soils—minerals in the geological sense— are almost all compounds, and usually complex ones at that. And they are insoluble, which is significant as vines can only take up dissolved matter. Directly relating minerals in wine with those in the vineyard soils implies that they are the same things. However, although ultimately linked, they are not the same. For example, the single most widespread geological mineral in vineyards is an intricate affair, consisting of various permutations of sodium, potassium, calcium, aluminium, silicon and oxygen strongly bonded together in a crystalline lattice to form the compound called feldspar. Of course, the nutrient minerals in vines and wine are very largely derived from the geological minerals ® 707-938-1300 info@acrolon.com 64 p r acti c al w i ne ry & v i ne yard MAY 20 13 (unless there is contamination of some kind), but by processes that are complex, protracted and constantly changing. In other words, there is a major disconnect between the two kinds of minerals, both within the vineyard itself and through to the finished wine. Take the example of feldspar. Its constituent elements are ionically and covalently bonded into a crystalline lattice that gives a grain of the mineral strength and rigidity. Not only that, but normally the feldspar particle will be bonded together with a host of other mineral grains to form the solid, rigid aggregate that we call rock (or, if fragmented, stones). To be accessible to vine roots, therefore, these elements have to somehow become loosened and abstracted from the outer boundaries of this aggregate of crystal lattices and taken into solution. This may utilize mycorrhizae and other microbiota, but these function mainly in rich, shallow soils that are usually not taken to produce wines with minerality. The other chief mechanism involves swapping any cations in the adjacent pore-water with either humus (which is also found mainly at shallow levels in fertile soil) or the surfaces of suitable geological minerals.