What Does Minerality Really Mean?

August 1, 2020
by Raj Vaidya

There are many buzzwords volleyed around in the wine business these days which invoke spirited and controversial responses. The conversations around what ‘natural’ wine means, the use of sulphur, the effect of climate change and conversations about additives often lead down the path of having to “agree to disagree.” On the subject of minerality in wine though, it seems, most wine professionals and wine loving amateurs are in agreement that there is something we all notice in certain wines like Champagne or Chablis which has a similarity to the soils from whence said wines were grown. However, the scientific community has brought into question whether the chalk found in Champagne or the slate soils of the Mosel actually impart any mineral compounds at all to the grapes themselves. Indeed, it appears when looking through a scientific lens that the plant itself is not capable of extracting any quantifiable mineral content from the soil. Yet Chardonnay grown in the Kimmeridgian soil of Chablis is noticeably different from the same grape grown in very different soils in the Côte-Dor just a short drive south, grown in limestone. The climates are quite similar, the grape variety the same, viticultural practices overlap a great deal, yet the aromas and flavors of the wines, their terroir expression, is completely different. So how can this be explained?

We tend to associate the word terroir with the type of soil, but in fact the term concerns quite a bit more than just the rocks and dirt beneath. The weather patterns of a place, elevation above sea level, depth of the mother-rock and water table, and the winemaking traditions (i.e. the actions of winemaking and farming) all contribute to a ‘terroir identity’ of a wine. But surely the soil, subsoil and rocks beneath are very important and impactful. How compact or heavy a soil may be affects drainage. The soil’s PH is important as certain grape varieties are known to do well in high or low PHs. In certain soil types including sand and slate, the loose sandy texture of the underlying rock make it impossible for phylloxera (the devastating louse which is the bane of naturally rooted vines the world over) to subsist. This allows for ungrafted plants to flourish in areas like the Mosel in Germany and Colares in Portugal. And of course, the mineral and elemental make-up of the soil does clearly have an effect on the types of vines grown and how they fare. Nitrogen, phosphorus and potassium content matter as with any organic materials, but mineral salts in soils like limestone, clay or even gravel will have an impact on the growth of the plant. It’s worth noting that the scientific community is not saying that the impact of soil on plants is false per se. Rather, what is being stated is that the vines themselves are not capable of extracting such minerals from the soil and channeling them into the fruit. The grapes grown in Champagne have no evidence of ‘chalk’ in the actual grapes, because the vine cannot remove that mineral content from the soil and transfer it to the grape. This is an important distinction from the claim that flavors reminiscent of these minerals exist in the wine. Very often, the scientists can only permit what they can prove in a laboratory, and so since such minerals do not transfer to the grapes they assume that we wine tasters with our flowery descriptions of ‘slatey Mosel Riesling’ and ‘gravelly Pessac’s’ are simply caught up in a fallacy. We must be ascribing these characteristics to the wine via our imagination, and not based in reality at all. But from our perspective, there is no question that something is translated from the soils. So if it isn’t the actual mineral content, what might it be? Those of us in the trade have learned to trust our senses when tasting, and any observation of a blind tasting of wines from classic European regions will exhibit how an experienced taster can identify wines as being from a specific place, at least some of the time. And when a good and experienced taster is wrong about the place itself, I’ve noticed that it’s often the case that the soil type of the place they picked is similar to or the same as the soil type of the wine’s actual origin. The fact that we have developed a common vocabulary in an otherwise fairly subjective field is further evidence that we aren’t perpetuating a fallacy about mineral flavors in wines. Yet it remains something difficult to prove in a lab… In conversation with Benoit Marguet, a vigneron and wine producer in Ambonnay in Champagne, some years ago I got a glimpse into what I believe may well be the best explanation for this phenomena. Benoit ascribed the ‘mineral’ characteristics we observe in wines as what he called a ‘memory’ of the place, as transmitted through water. This opened my eyes, as I thought it not only a brilliant and poetic way to describe the relationship between soil and fruit but also a very plausible explanation for the phenomena. Water, of course, is vital to a plant’s survival and defines the plant’s character in important ways. In the case of viticulture, it is always stated as a goal for the vines to suffer for nutrients in the top soil, forcing the roots to dig deeper into the sub-soil and rocks to ‘access’ such complex flavors as we’ve been discussing. But what the roots are really doing is accessing water from within the rocks. Certainly, water is known to take on mineral content of its surroundings. And furthermore water is known to be able to transmit a whole host of things, be they mineral or energetic, even electric. So it makes sense to me that the ‘message’ of the mineral content can find its way into the grapes and eventually the wine via the water the plant extracts from the earth. Undoubtedly this will not suffice as proof for someone in a lab coat, but at least there is a clear conduit between the two that we can identify. When I first visited the Mosel valley years ago I was struck by the slate hillsides and how much they smelled like a rock quarry. The whole valley was warm and sunny that year and though I didn’t notice aromas of topsoil (there’s nearly none) or organic matter (ditto) in the vineyards, I did get a slight sense of that smokiness one finds in certain Rieslings, albeit having been a vague one. Some days into the trip I was hiking around the Treppchen Vineyard in Erden in the middle Mosel, where there is a small trail leading amongst the vines through a small wood to the top of the incredibly steep and picturesque Prälat vineyard. Along the way some clouds gathered and it started to rain, a humid summer shower. Immediately, my perception of that gun-flinty smell was awakened again, and the whole vineyard smelled exactly like the old bottles of Dr. Loosen and Christoffel Auslesen from these very vineyards that I’d tasted early in my career. The rain water helped communicate that element of terroir to me so clearly in that moment, and it defined my ‘smell (and taste) memory’ of Mosel wines from that moment forward.

Tesson in Meursault