Everything you need to know about minerality in wine

During the preparation of our new Essential Guide to Italian Wine, I tried to convince my collaborators to substitute the term ‘mineral’ with other definitions. I think the term is overused, not clear and used in a figurative way, thus making it more than questionable. Some agreed with me while others did not. For this reason I have decided to share with you, readers and collaborators, what Luigi Moio, a professor of enology at the Federico II University in Naples, had to say about the matter. After that the debate is open.

“The term ‘mineral’ was coined in Alsace essentially to describe certain notes that Riesling has and which are often associated with those of kerosene, due to principally to the presence of 1,1,6-trimetil-1,2-diidronaftalene (TDN). The term was then adopted in Burgundy and often referred to the aroma of flint, most commonly pyrite which is used to create the sparks needed to ignite gunpowder or the flame in cigarette lighters. Pyrite is an iron sulfide and a source of sulfur for products like sulfuric acid. When warmed it gives of a host of sulfuric odors including the one of being ‘reduced’. Thus the note of pierreà fusil, which reminds me of the years I spent in Burgundy and which is often associated with ‘minerality’, is nothing more than a scent of sulfur created by a slight reduction and which, in fact, recalls earthy sensations. Naturally, when these notes are immersed in the aromatic wealth of Chardonnay - or in Alsace in Riesling, Gewurztraminer and Muscat – they are extremely pleasing. In Italy there is a lot of confusion over the term ‘mineral’. Minerals are found in the Earth’s crust and are almost all solid at room temperature and are often in crystal form. Strictly speaking, the soil cannot be identified in any wine, given that minerals are not volatile and are thus odorless. The odor that one senses in smelling a stone, for example a rock at the sea, is created by the eventual presence of contaminating organic agents. Sulfur is a non-odorous and unflavored nonmetal that is most commonly found in crystal form and has an intense yellow color. Only after it is subject to combustion does it interact with oxygen and produce sulfur dioxide which does, on the other hand, have a distinct odor. French researchers in Burgundy carried out a study on what constituted ’minerality’ and concluded that there is no unequivocal and important sensorial definition for this term.

Even if it has no clear sensorial significance, the term is very popular probably because it recalls an almost physical rapport with a place and is used to designate origin. I, too, use the word but associate it more with acidity and extreme sensorial purity, especially in white wines. The uncontaminated purity of the mineral is what allows the wine to stand the test of time. A wine with mineral notes is, for me, a very pure and uncontaminated wine in which the deterioration of the aromas is reduced to the maximum. With time it is possible to recognize the sensations of the grapes used to make the wine and, in the case of a cru, these are extended the longest possible”.