So far in this personal exploration of minerality (by personal, I mean I’m trying to understand this wine-tasting phenomenon as much as you are) I have discovered that there are no easy answers to the issue of minerality in wine. It doesn’t reflect the magical absorption of rocky minerals (feldspar, quartz and the like) from the soils. Nor does it reflect the absorption of chemical minerals (ions of calcium, manganese and so on) from those same soils. Whatever the answer to the minerality question, it is clearly going to need some protracted thought and head-scratching. With that in mind, perhaps we had better decide exactly what we are talking about when we refer to ‘minerality’ within a wine.
Unfortunately, not even this is without controversy.
First, let’s turn to the palate. Is minerality a flavour – the essence of wet stone, rain-splattered slate, hot schist and so on drifting across the palate – or is it more of a “taste sensation”, an extra structural component of the wine to be listed alongside tannin, acidity and residual sugar? The truth is, the term seems to be used in both ways.
First, I have seen the term ‘minerality’ used where the author is clearly communicating a well-known flavour of the wine of the wine in question. Long before I first read the word minerality within in a tasting note, I was aware that Mosel Riesling often had a slatey flavour to it. Likewise, Chablis was also recognised to have stony edge, said by many to reflect the classic Kimmeridgian limestone of the premier and grand cru vineyards.
Second, and this is perhaps a more precise meaning, when the term crops up in a tasting note the author is I think often referring to what I call a “taste sensation”; not a flavour as such, but a structural element of the palate. It is difficult to describe, but the best analogy (and I accept that this stretching the definition of an analogy a little) is that it is like the dry, tingling-puckering sensation that you might get from sucking on a pebble. It is not so much the flavour of the pebble (this is a flawed statement by the way – I’ll come back to why this is so in a minute) but more the effect it has on the ‘shape’ or ‘feel’ of the wine.
This “taste sensation” leads to an almost inevitable confusion between minerality and acidity, one that is confounded by the fact that minerality tends to be a feature of cool climate, high-acid white wines – think Chablis, Sancerre and Muscadet, for example. But whatever the cause of this ‘minerally’ sensation, I think we can be clear that it is not the same as acidity. The two feel very different on the palate, and our persistent inability to identify an explanation for this minerally sensation should not lead us to draw overly simplistic conclusions regarding a potential role for acidity. Indeed, some wines may be acidic but not minerally. And probably (although I’m struggling to think of one off the top of my head) vice versa.
Is minerality merely flavour or “taste sensation” though? I would contend it is not, as in many minerally wines I sense this minerality in the aromatic profile. This is a statement that is likely to incite some debate, because I have noted some wine professionals state with certainty that minerality cannot be smelt. This to me seems to be patently incorrect, however, for three reasons:
(a) a major rationale for the statement is that minerals such as feldspar are not volatile, and therefore can not be smelt. But we have already agreed (I hope!) that what we call “minerality” is not the presence of actual “minerals” in the wine. In the same vein, old Rioja does not really contain strips of leather and roasted game, and maturing left bank Bordeaux does not really contain cigar boxes, pencil shavings and the inside of a dusty old cabinet. I realise these analogies are a little flippant, because minerality as a structural element is perhaps more complex than these ‘mere’ aromas and flavours, but you get the point I hope. Minerality isn’t minerals, so let’s stop fencing in ‘minerally’ characteristics according to the physical properties of minerals.
(b) there seems to me to be a significant cross-over between minerality and what we call reduction. The issue of reduction in wine is another can of worms, as like minerality what we call ‘reduction’ probably isn’t true full-on reduction but something else, namely the presence of volatile mercaptans and complex sulphide molecules. This is something I will explore in more detail in the future, so for the moment suffice to say that “reduction” is very aromatic, as are “minerally” aromas in wine, and in some wines – especially Pouilly-Fumé I have found – I can experience some difficulty teasing them apart. That wouldn’t be the case if ‘minerality’ weren’t aromatic.
(c) in my experience, time and time again I come across wines which display aromatic minerally elements. The classic cool-climate white wines that display minerality I have already mentioned, but it can be found in red wines too. A recent memorable example was when tasting with Jonathon Maltus at Château Teyssier earlier this year; he likes to compare and contrast Le Carré (clay over ‘ordinary’ limestone) with Les Astéries (clay over calcaire à asteries, the classic hard, fossil-encrusted limestone of St Emilion). Just nosing the wines, it was as clear as day that the latter had a much more minerally aromatic profile than the former, and it wasn’t necessary to taste them to tell which was which. Some aromatic distinction – which I found worthy of description as ‘minerally’ – allowed me to distinguish between the two wines.
Before I finish I just want to return to the statement I made – regarding the ‘flavour’ of a pebble – which I wrote was flawed. To understand the problem with describing the flavour of a pebble we must return to the my first minerality post when I laid out some minerally chemical formulae for a small selection of minerals including feldspar, muscovite and biotite. These are large, inorganic molecules that are insoluble in water and, as discussed in (a) above, are non-volatile. As such, these substance cannot be ‘tasted’. That doesn’t upset our notion of what might cause minerality, because we have already discounted any thought that these giant mineral molecules are somehow absorbed by the roots and deposited in the grapes ready for the fermentation vat. But it does beg the question – pebbles smell and taste of something, so if it isn’t ‘pebble’ just what is it? Is it the cause of minerality? Or is ‘reduction’ more important? Or is ‘minerality’ something else altogether, some aspect of winemaking not yet covered? These are questions I will have to come back to on another day.