Today, the buzz word among wine’s chattering classes is minerality. You’ll hear it used to describe a broad range of sensory perceptions met in wine — from loam and humus to gravel, slate, flint, wet stones, chalk, even basalt and coal. But since few of us will have actually sampled any of these materials, it seems fair to ask how we know what they taste like (if anything), and — an even more fundamental question – whether minerals can ever be taken up by vines and contribute flavor to wine. Short answer: No.*
To explain, let’s begin by pointing out that minerals are generally described as falling into two categories: nutrient and geologic. The former exist as soluble elements like magnesium, zinc and iron, are present in our food and bodies and are important for health. The latter are compounds that form the physical framework of rocks and soils and are generally insoluble.
To the degree that some tiny amount of nutrient minerals are made use of by vines and taken up in the form of ions, their presence in finished wine is extremely attenuated. They’re challenging to detect even in a laboratory and exist in concentrations that put them below any sensory threshold. But these points are moot anyway, since mineral nutrients are themselves entirely flavorless.
Wine is not like mineral water which absorbs and holds in solution an array of inorganic compounds (magnesium, calcium, bicarbonate, sulphate) soaked up in long subterranean sojourns. It’s these solids that give mineral water its characteristic briny, bitter, alkaline character. But this process doesn’t describe the interaction of geologic minerals with vines or their fruit. Flint present in soil cannot translate into “flinty’ flavors in wine.
We are personally partial to the view that minerality as a term current among wine enthusiasts is really just a way to describe a spectrum of flavors generated by fermentation that don’t read as fruity or leafy or herbal or spicy, but which we struggle to give a name to. As always, when facts are in short supply, the imagination steps in.
The most likely research-based explanation being bruited suggests that these stony, fumey effects owe their existence to sulfur compounds produced naturally in the fermenting vat. Wine chemistry is so complex that we still don’t really know everything that’s going on. Until we do, the prudent approach would be to temper speculation, unsatisfying as that may be.
While leaving certainly to a future generation, we contemporaries can at least rally around one indisputable if not particular science-based conclusion: Wine – fruity, leafy, herbal, minerally or otherwise – rocks.