Vineyards, Rocks, and Soils – book review

This is a review of Vineyards, Rocks, & Soils – The Wine Lover’s Guide to Geology, by Alex Maltman, a book published earlier this year, by Oxford University Press which probably explains the unnecessary comma in the title. I picked it up recently from Wordery for just over £20.

My first impressions were very favourable. It is what I have come to think of as a classic-style book: with text organised in a logical sequence and designed to be read linearly from beginning to end. And the illustrations support the text rather than being the main focus of the book. Call me old-fashioned, but that is the way I like the world, and I already have more than enough books for the coffee table thank you. My only criticisms about the presentation is that the text on some of the illustrations is difficult to read due to its size and/or poor contrast, and that the colour illustrations are bound as plates in the centre for the book. I appreciate this is done to keep costs down, but it nevertheless makes the book less convenient to use. Close to the relevant bit of text, there are also grey-scale versions of the plate illustrations, but the grey-scale figure captions do not reference the plates, so I was more than a little bemused to see a grey-scale image used to illustrate the “striking red color” of the terra rossa soil, without realising the image also existed in colour elsewhere. Neither do the colour images reference the grey scale versions, or even duplicate the figure captions, so if you try browsing the colour plates you have no idea what you are looking at. (In case you are wondering, if there is a colour version of the figure it is the main text that links the two versions, by referencing both of them.)

The book starts at the atomic level, and works its way up in scale through two chapters about minerals (the chemical compounds that comprise rocks), then moves on to the three types of rock (sedimentary, igneous and metamorphic). That is followed by a couple of chapters about folds, faults and joints in rock, and how geology influences landscape. In this initial two-thirds or so of the book, there is little mention of how the geology influences wine, but the author does take pains to give examples of the minerals, rocks and landscape features under discussion in well-known wine regions and vineyards, and also notes how the geological terms are used on wine labels and in promoting the wines.

Building on that basis, the rubber then makes firmer contact with the road as we learn about how this geology affects vines and wines. Largely it is indirectly through the soil, so we look at how soils are created, mineral nutrients, minerals in wine, and a more general look and the concept of terroir. This is followed by a chapter on geological time, and the names of the geological periods. This seems like an odd place to discuss geological time, and to an extent the author seems reluctant to discuss it at all, as he maintains the age of the rocks has no bearing on the soils, vines and wines. But it is nevertheless a favourite topic of wine-writers, and of people promoting wines and wine regions, so he thought it should be mentioned. Finally, the book ends with an epilogue discussion of the  how the geology of the vineyard affects its wine’s taste.

At the end of the book, I felt I had grasped the broad thrust of the main geological content, but I must admit I skipped through some of the detail, and very quickly forgot some detail I did concentrate on. But I still have the book, and with its excellent index, and use of a bold typeface to indicate where new concepts are explained, it will be good as a reference work to help keep myself geologically sound in my writing.

Maltman seems to have become a bit of a bête noir amongst proponents of minerality and terroir, at least those who see things in black and white terms. But I think his attitude as expressed in this book strikes the right balance in a very measured and tolerant way. Nevertheless, and quite reasonably in my opinion, he does maintain a degree of scientific scepticism. I tend to agree with him on most of these issues of debate.

Also, while pointing out that wine people often do not use geological terms correctly, I think he is also very understanding, admitting that the subject can be very confusing, and that even geologists change their minds and do not always agree amongst themselves. However, when he sees important geological errors in the wine world he is keen to flag them up. A good example is the common confusion between the very different rocks called tuff (volcanic) and tufa (precipitated from cold water).

My final point is that Alex Maltman is an academic who has a wealth of experience in the teaching of geology, and it shows. He knows how to develop the subject in a logical way, how to explain topics that are likely to confuse, and how to lighten the mood with the odd anecdote. And he writes with authority. This is in marked contrast to the more journalistic style of writing where the author travels the world to “find out”, recording interviews with experts en route, and often requiring the reader to fill in the gaps and assemble everything to make a coherent whole. That journalistic style appears to be increasingly popular – but it is not for me.

Solid evidence for terroir influence on wine flavour

I recently stumbled across what seems to be solid evidence for some effects of terroir on wine. It is not new research, but for some reason it had managed to elude me, and was only brought to my attention by John Winthrop Haeger’s book Riesling Rediscovered. The research is published in [1] and [2] – see end of this post. As the latter reference is available on Google Books almost in its entirety, that was my main source of information and where I found the figure shown below.

Twenty-five different Riesling vineyard sites were studied: 12 in the Pfalz, and 13 in the Mosel, Ahr, Nahe and Rheinhessen. The substrates yielding the soils of these sites included limestone, sandstone, greywacke, basalt, slate, porphyry, and breccia from the rotliegend age. The vintages 2004, 2005, 2006 and 2007 were assessed 8 months after the harvest by panels of 13-20 trained judges. The grapes were picked at optimal ripeness, as determined by the estate owners, one portion from each site being vinified as normal by the estate, and one portion subject to a standard winemaking protocol that was the same for all sites. The wine made by the estate was evaluated in duplicate, while standard process wine was evaluated in triplicate.

The results of a discriminant analysis are shown below (click on the figure to get a larger version). If I understand the point of a discriminant analysis correctly, it here means that two functions of the flavour profiles, F1 and F2, were found such that wines of the different rock types cluster when F2 is plotted against F1. Thus, if you know the flavour profile of the wine, you could calculate F1 and F2 and stand a good chance of predicting the rock type by checking where the point lies in the left hand graph.riesling_terroir_differencesNecessarily, there were many details omitted from the conference paper, so it is difficult to judge the quality of the research, but to me nothing stands out as being obviously flawed and I would assume the work is sound. As such, for me it is the first convincing evidence for the soil substrate type having an impact on flavour profile. All the other evidence I have seen has been non-blind and anecdotal, and whenever blind tasting has been used terroir differences seem to disappear, even for people who would generally be regarded as expert tasters.

One interesting question about this research is to what extent the experimental protocol was essential in revealing the terroir effect, and to what extent it would also be clear to expert but non-trained tasters tasting blind. In other words, now necessary is the training and the discriminant analysis in uncovering the important of terroir? Also, more generally, I wonder how applicable the results are to other grapes and regions.

See my previous posts on the subject to understand my mildly sceptical attitude to terroir. I think I would still describe my attitude in the same way, but it has certainly just shifted considerably in the positive direction. However, in the introduction to the article I summarise here, it is made clear that terroir is hugely important in marketing, as a unique selling proposition, and as point of interest for punters. Marketing was the driver for this research, and whenever marketing is involved my bullshit detectors start twitching with heightened sensitivity.

[1] Andrea Bauer et al, “Authentication of Different Terroirs of German Riesling Applying Sensory and Flavor Analysis”, in “Progress in authentication of food and wine”, pp 131-151, American Chemical Society,Washington, DC, 2011

[2] A Bauer and U Fischer, “Factors causing sensory variation in Riesling wines from different Terroirs in Germany”, in “Oeno2011: Actes de colloques du 9e symposium international d’oenologie de Bordeaux”, pp 1087-1092, Dunod, 2011

Tasting French Terroir – book review

tasting_french_terroirThis time, I review the book Tasting French Terroir, subtitled The History of an Idea, by Michael Parker. At Amazon it costs around £20.

Firstly, the title: I am not really sure why the word tasting features here at all, as it  has a surprisingly small role in the book, even if food and drink in general get more coverage. It is however very much a history of the idea of terroir in France, going back to the 16th Century, and with a few mentions of classical antecedents. There is little mention of terroir in other countries, but as far as I know it is a concept that is exclusively French in origin, so I suppose that is fair enough.

The book is serious and academic, so not a light and quick read. But on the plus side for someone with limited time, it is not as daunting as it might first appear, as the actual text finishes on page 164, the remaining third or so being given over to notes. This scientist-cum-engineer had to check on the meanings of quite a few words, but beyond that the language was clear, precise and nicely crafted.

My big lesson from reading it was the sheer range of historical views on what constitutes terroir and how desirable it is. Thus, it puts the modern idea of terroir firmly in its place: one interpretation amongst many, though an interpretation that was glimpsed at in various stages of history. I attempt below to give an overview of some of the ideas of terroir discussed in the book.

Even on very fundamental questions, there were widely divergent views. We tend now to see terroir as conferring different characteristics, all positive, on food and drink. But another perspective emphasised more the effect of terroir on quality. In this view, some terroirs were better than others, and if the connoisseur wanted the best produce, then only the very best terroir in France could yield it. Others saw terroir more from the farming point of view. Thus, when planting a certain crop, the correct terroir must be selected to get a good yield.

However, terroir had relevance to a lot more than food and drink. It was of course also about plants, trees and animals, but more significantly a lot of discussion also focussed on the terroir characteristics of people. This included their appearance, behaviour, dialect, and even the style and quality of their poetry.

There is also the issue of whether terroir characteristics are desirable or not. For long periods of French history terroir influence was regarded as negative, and something to be supressed in favour of good Parisian taste, and that of the French court. But at other times terroir was definitely positive, or it was more nuanced. For example a degree of terroir character could be positive, but it had to be tamed by Parisian culinary arts. Others were of the view that there were both good and bad terroir expressions.

There is little in the book about the mechanisms by which terroir worked its magic, so I presume it was not discussed much in the source texts either. As today however, it seemed that soil, water, climate and landscape were all important factors. There was at one point a rather literal interpretation of goût de terroir, which suggested that you could get it water that was first shaken with soil. Apparently the flavours in the water were also present in the produce of the land. Otherwise there was little indication of how to recognise the goût de terroir.

There is also little coverage of how early views of terroir contributed to the Appellation d’Origine Contrôlée system in the 20th century, and how ideas in the late 20th and early 21st century developed. Perhaps there is another book in those topics. I look forward to reading that book should it become available, and also to seeing future developments in the concept of terroir.

Vines as a component of terroir

I am probably a lot more sceptical about the concept of terroir than most wine lovers.  Nevertheless, I do find the subject fascinating, and it leads to many insights.  When people speak about terroir, they use it to refer to the vineyard rock, soil, drainage, aspect and climate.  Some will add viticultural and winemaking practice to the list, providing it is traditional for the region.


But what about the vine stock of the vineyard?  I am sure most would argue that the vines planted, however traditional, are independent of terroir.  However, it has come to my attention recently that there is maybe an alterative view.  Here is what Dr Jules Lavalle has to say in his 1855 book Histoire et Statistique et des Grands Vins de Bourgogne – translated by Charles Curtis in The original Grand Crus of Burgundy:

[The value] is also in the age of the vines, which for Cos de Bèze notably, goes back 12 or 15 centuries during which the soil, purged of all foreign plants and removed from all addition, is enriched only by the detritus of the vine, and has created an exception and perfectly homogenous terrain, with which the vine, which has never changed, is in some fashion united and acquires the properties which can be given only by the conjunction of all these conditions.  Such is the privilege of the grand crus of the Côte d’Or that certain Belgian amateurs refer to them as  having “race” [lineage] and certain English refer to them as “being of good family”.

This was written at a time when the concept of terroir did not exist in quite the same way as it does now,  and I have no evidence that the view was common in Lavalle’s day, but I think it remains an interesting perspective on what we would now probably call terroir.

When the author writes about unchanging vines over a periods of 12 or 15 centuries, he is not referring to the age of individual vine trunks, but presumably to provignage over that period of time – the practice of propagating vines by burying a shoot and allowing it to develop roots, something only possible pre-phylloxera.  Thus, in a sense, the vines will have been in that vineyard over that period.  At the very least, the mix of clones in the vineyard will have remained stable.  It will not be identical because the vigneron will chose to propagate from the most promising vines, and there will also be genetic mutations.  Nevertheless that idea of connection between the vines and the vineyard over many centuries remains powerful and evocative, and something we have now lost in our age of grafting onto American rootstock.  Even if scions from the same vineyard are used, somehow the link seems now to have been broken.  The introduction of grafting may not merely have affected the quality of the wine, but arguably an aspect of terroir has been destroyed.

It is also noted that the vineyard was only fertilised by detritus of the vine, which I take to mean pruning cuttings and marc.  This too emphasises a connection between the vines and the vineyard, and I would go so far to say that it seems more intuitively appealing than even biodynamic treatments, which would often have to made from ingredients sourced from outside the vineyard.

But stepping back a little from Lavalle’s proposition, and returning to my usual sceptical self, how important do I think the connection between vine and vineyard is?  Let’s just say that when I am told that Burgundies from vineyards either side of a footpath are markedly different due to terroir, I do wonder how much of that is really down to different clones of Pinot Noir or Chardonnay, or indeed rootstock.  But perhaps there is no conflict, and traditional vines should be counted as part of terroir even in this modern age of grafting.

Update 12/01/16: I have just been reading “Terroir and Other Myths of Winegrowing”, and was interested to note that according to Aristotle, vines and other plants were quite literally part of terroir. That is to say that soil contained corpusles of vines, which were in effect minute versions of the vines we can see, touch and make wine from. These corpusles were taken in by the roots to become the actual vines. This theory was accepted by some plant anatomists at recently as the early 1700s. In medieval times, there were also alchemical ideas about the soil being physically transmogrified into plant material. It is less clear what the man-in-the-vineyard thought about all this, but presumably they were not in touch with the latest scientific thought.

Terroir scepticism again

Three years on and I am still waiting for someone to take on my Terroir Test and show positive results.

I have not been holding my breath for the Terroir Test in particular, but I was rather hoping that someone somewhere would come up with an interesting example of terroir differences being consistently identified blind.  Instead, in the last edition of The World of Fine Wine, there were another couple of failures reported: the failure to be able to identify granite and limestone terroirs in Alsace Riesling, and the failure to be able to identify Burgundy villages.

I shall add those failures to my list, which earlier included the Judgement of Paris, where Bordeaux and Burgundy was confused with American wines, and a tasting reported in Jasper Morris’s Inside Burgundy, where the different levels of Clos Vougeot were not identifiable.  Plus many incidents from personal experience of course.

Those examples do not demonstrate that terroir does not exist, but they do in my opinion show that many who talk and write about it should be far less glib.  I already try to tread carefully in this area myself, but maybe even greater care is in order.

On a more positive note, someone did point out to me that the best blind tasting teams perform rather well, at least in being able to identify the villages and vineyards in classic wine regions.  I’d like to better understand how well they perform, and how they do it.  I suspect that a lot of focussed hard work and practice is involved – a commitment that most wine-lovers, writers and critics would not be prepared to make.

Le Nez du Terroir

The trend may have passed you by, but dirt tastings are becoming increasingly popular.  Yes, really!  Punters are invited to smell and taste soil along with the produce of that soil, and the astute taster will spot the ways in which the produce relates to the earth in which it is grown. Here are videos of a couple of dirt tastings to show you what goes on:

To really understand why your Burgundy tastes of farmyard, I am sure you can’t wait to get the soil of your favourite terroirs in your mouth.  Indeed there are an increasing number of producers that will let you do just that, encouraging you to taste their soil. But be careful of those vineyards where nasty chemicals are used.  It is probably best to stick to organic and biodynamic vineyards where only manure and copper sulphate are used.

Seriously now, please don’t put any soil whatsoever into your mouth – I will not be responsible for any ensuing medical problems.  I suggest you sniff only, and the simplest way is to do it is to use the latest addition to the Nez du Vin range – Terroirs.


This is one of their smaller collections of aromas, but nevertheless it makes a stirling effort to cover a wide selection of terroirs from around the world. They include both great terroirs and lesser ones, enabling you to understand the influence on wine quality.

1. Bourgogne
2. Romanée-Conti
3. Montrachet
4. Bordeaux
5. Château Latour
6. Château d’Yquem
7. Liebfraumilch
8. Bernkasteler Doctor
9. California
10. Screaming Eagle
11. South Eastern Australia
12. Grange

Nez du Vin do not specify exactly how they transform the soil into a form that can be appreciated on the nose, but I understand that that the Romanée-Conti sample is processed on root days, and stirred with clockwise and anti-clockwise vortices.  A good representative sample of soils is used, which is of particular importance for the larger areas covered.  Thus, just as the wines of South Eastern Australia may be a blend from all over the region, so is the soil in number 11.

Prices vary, so it is worth googling for the best deal, but as with all Nez du Vin kits of this size be prepared to pay around £50 or more. For what is essentially soil extract, is it worth it?  I think you get out of the kit what you put in in terms of effort.  I had to return my loan kit after 7 days, and in that time I couldn’t really distinguish between many soils.  Someone on the left hand video above commented that one soil was “quite subtle”, while another was “very subtle”, and I have to say that pretty much sums up the range of smells I could distinguish.  Having said that, after a lot of practice you could probably learn to recognise each of the 12 soils, and impress any friends you might have left at that point.  It probably helps if you have glasses of Blue Nun and Romanée-Conti to hand while you are sniffing the terroirs.  In fact a good idea for Nez du Vin’s next project would be to sell a set of bottles containing the corresponding wines, so you have all you need in two smart-looking boxes.

Update:  This post was taken seriously by a few people when first posted, so now April Fools’ Day is well gone it is probably only fair to point out that the Nez du Vin part is a JOKE.  However the introductory bit about terroir tasting is (as far as I can tell) completely true.

A sense of place

When I was learning “how to appreciate wine”, I seem to remember being told that a quality wine could be identified by its length and complexity.  I am not sure I was totally convinced –  shouldn’t the wine taste nice too, or doesn’t that have anything to do with quality?  Anyway, it seems now that length and complexity have been replaced by sense-of-place, at least by critics and wine writers if not wine educators.  In many ways I find sense-of-place as a sign of quality even more disconcerting than length and complexity.

Setting aside anthropomorphic objections for a moment, I really struggle to understand what a wine having a sense-of-place means.  If it implies that it is different and interesting, and that it is not created by wine makers in response to a spec from the marketing department, that does sound like a good thing.  But I think the implication is that the wine smells and tastes in a way specific to its area – essentially it is another way of saying that it has typicity, or is typical of its terroir.

I might just about allow that a regional specialist might have an idea about what sense-of-place means for the wines in their area of speciality.  But even then most experts seem to be reluctant to describe the typical flavours, and seem to find them difficult to identify when tasting blind.  However, my scepticism turns to cynicism when journalists are flown out to some unlikely region and declare the wines to have a strong sense of place.  Do they really know what wines from that area taste like, as opposed to the wines just around the corner for example?  And even if they do, are they than able to rate the sense of place and declare it to be strong or weak?  I don’t think so.  Maybe they are actually merely saying the wines are different and interesting.  Who knows?

Also, there seems to be an implicit assumption that the wines with a strong sense of place come from a good place. Given a choice between a Montrachet with a slightly deficient sense of place on the one hand, and  a wine from the irrigated plains of South Eastern Australian with a strong sense of place on the other, I’ll take my chances with the Montrachet thank you very much.

Perhaps a large part of my argument depends on my assertion that the writers of tasting notes are poor at identifying regions of origin.  I could easily justify it, and will do if asked.  But I don’t want this to come over as anti-expert/snob/connoisseur rant.  I prefer to leave it more as an appeal for more meaningful wine language – a defensible language that stands a chance of being understood by newbies.

Eucalyptus, garrigue and terroir

We have known for some time that eucalyptus trees are responsible for the eucalyptus nature of some Australian wines, but now the mechanism for the transfer of the aroma from tree to wine is clearer. Dr Dimitra Capone recently presented research (Update: that link was broken for me last time I looked, but there is a later article here) that shows that most significant source in wine comes directly from bits of eucalyptus tree that get collected along with the grapes at the time of harvest.  Even for hand-picked grapes, the number of eucalyptus leaves that find their way into the fermentation vats can be sufficient to give eucalyptus notes to the resulting wine.

This got me thinking about garrigue, which is often noted on wines from Southern France.  Assuming the notion of garrigue in wine is not entirely fanciful, could it be that it gets into the wine as MOG (Matter Other than Grapes) in the same way that eucalyptus does?  It seems totally plausible to me.

So, do garrigue notes count as an aspect of terroir if they get into the wine as literal bits of garrigue?   And what of eucalyptus?  Unlike garrigue, many would say that eucalyptus notes are undesirable, but do not they also help create a sense of place?

Incidentally, I also know that at least one elderly Languedoc vigneron in the 1990s deliberately used sage bush to improve the flavour of his wine. I don’t say this by way of exposing a scandal, as the wine was probably mainly for consumption by family and friends, but I suspect if one family did it there were others too. By a broad definition of terroir that encompasses local wine-making practice, you could maybe even construct an argument that deliberately added garrigue is terroir.

(Image courtesy Vera Kratochvil)

Minerality in wine

Various online wine forums were buzzing with discussions on minerality a few weeks ago.  I have taken part in the discussions on the UK Wine Forum and WLDG, and Jancis Robinson also joined in with a contribution in the FT on the subject.  What sparked it all off was a survey designed by Graham Reddel for the WSET Diploma.  If you think you might want to take part in the survey, it is probably best if you click on one of the forum links above to get Graham’s introduction as well as the link to the actual survey.  If you are going to, please do it now – before your mind is polluted by what I have to say on the matter!

I found the discussions fascinating, and after it all died down I felt a strong need to pull together my own thoughts on this broad-ranging subject.  This is the result…

A bit of history

I find it interesting that the use of the word minerality in tasting notes, is a relatively recent phenomenon.  The chart below shows its rise in usage in CellarTracker notes.  Before 1999 there were only 3 usages: 1 in 1989 and 2 in 1998.  I did not include those in the chart because they were early days for CellarTracker, and too few notes to draw conclusions.  After 1999 the trend is clear – the term was used very little before 2002, and then between 2002 and 2004 it really took off.  It seems as though the increase in usage is perhaps now tapering off, with the first 4 months of 2012 showing a slight drop.

Mentions of the word minerality per 1,000 CellarTracker tasting notes

A search in the wine literature, mainly books in my “library”, also leads one to the conclusion that minerality is a new descriptor.  I have checked in all of the following to a greater or lesser extent, using an electronic search in some cases, indexes and thumbing through pages in others:

Peynaud, The Taste of Wine, 1983
Noble, Aroma Wheel, 1984
Robinson (Ed), Oxford Companion to Wine 2nd Edition, 1999
Schuster, Essential Winetasting, 2000
Robinson, Wine Tasting Workbook, revised 2000
Broadbent, Winetasting, revised 2002
Broadbent, Vintage Wine, 2002
Jackson, Wine Tasting – A Professional Handbook, 2002
Lehrer, Wine and Conversation, 2009
Stevenson, Sotherby’s Wine Encyclopedia 5th Edition, 2011

In all these sources, here is what I could find on minerality.  Michael Schuster mentions it only in his glossary: “Suggestions to both nose and palate of stones: slate, granite, chalk, schist and so on, Especially in wines from the Loire, N Rhône, Bordeaux, Burgundy, Douro, Mosel, Tokay etc.  Fanciful?  Maybe, but real enough to many wine tasters; see TERROIR, p 129”.   And Jancis Robinson has an entry for “minerally”, also in the glossary only: “Smell of assorted minerals and a common component of fine Cabernet and Riesling”.  She put an asterisk by the word to indicate it is her own descriptor and not commonly accepted.  And that is it!  OK, earthy, sulphurous and petroleum notes are widely discussed, but those in my view are different to how most people use the term minerality.

I would hope that any modern book on winetasting, or wine in general, would discuss the concept of minerality as the term is now used so widely.  Goode and Harrop’s book of 2011, Authentic Wine,  has a section of 4 pages devoted to minerality, and it gets several other mentions in the book.

So what happened at the start of this century to kick-start the concept of minerality?  It seems Michael Schuster was literally ahead of the curve (as defined by CellarTracker) with his description in 2000.  Jancis Robinson too, albeit with a slight variant on the word, particularly if the same glossary also appeared in the  Wine Tasting Workbook’s precursor of 1983.  My guess is that a number of professional tasters started referring to minerality around 2000 and it took off from there, but I would love to know more precisely how it happened.

What does the recent conversion to minerality mean?  That’s another difficult question.  Have people suddenly discovered an aspect of wine they previously were oblivious to?  That seems unlikely to me.  A much more likely explanation is that they are giving a new name to the same nose and palate experiences.  Or the idea of minerality is perhaps one of the more fanciful wine descriptors that does not mean anything very precise when you analyse it, and it is mere fashion that dictates that modern tasters write about minerality – rather than, for example, a wine being like a pretty girl with a white dress dancing in a meadow.  I think its rise is linked with another concept gaining traction with wine writers: terroir.  When asked most people will say that it is naive to made a direct link between minerality and terroir, but when enthusing about a wine it seems it is all to easy to be able to taste the slate in which the vines were grown.  However it happened, once the concept of minerality was established it took on a new air of reality.  The question for many people now is not “what does minerality mean?”, but rather “does this wine have minerality?” and “what type of minerality does it have?”.

But personally I am stuck at the “what does it mean?” stage, and I think it is an important question – one I am going to address in the rest of this essay, er… I mean, blog post.  Please indulge me.

Definitions and facts

Leaving aside for a moment the sensations they invoke on the nose and palate, what exactly are minerals?  In common winespeak, my impression is that there is a loose definition and a tight one.  The loose definition includes pretty much everything that is not animal or vegetable, e.g. sulphur, petrol, salt, steel and graphite.  The tight one includes only rock-like materials: pebbles, slate, granite schist and chalk.  Neither of these corresponds particularly well to any of the definitions accepted by scientific bodies, but let’s not get too hung up on that.

Old vine growing in Douro schist

If we are talking about rocks only, we should be aware that very few rocks taste of anything.  The main common exception is halite – rock salt.  Geologists commonly stick rocks in their mouth to identify them, mainly by texture and hardness, so they should know.  But many people insist that rocks do have flavour, and I would not deny anyone’s experience.  I would just suggest that it may be some organic matter on the surface of the rock that they are smelling or tasting – geologists doubtless lick newly broken surfaces.  In a sense it does not matter.  But in another sense it does, because if it is organic matter on the surface of the rock, what they perceive as granite could be actually totally unrelated to the stone itself – if a bit of slate were found in the same environment it might taste the same.

Another possible explanation for the claimed taste of rocks might be synaesthesia caused by their texture and temperature.  I know of no firm evidence for this particular type of synaesthesia but from everything I have read about synaesthesia and taste, particularly the work of Charles Spence who has recently published a few articles in The World of Fine Wine, it would not seem at all surprising.

Finally, a few random facts:  1) Broadening things out from a consideration of rocks, metallic smells are now known not to derive directly from the metals, but from interaction with oils from the human body.  2) Pencil lead contains clay as well as graphite, so if your wine tastes like pencil lead it is quite possible that it is the clay you are thinking of.  Medical grade charcoal tablets are probably a better model for how carbon tastes, and as I remember them they are very neutral in flavour.  3) The chalk sticks you use to write on blackboards are not chalk, but gypsum.   All this may not be hugely important, but I think it does show that we need to be a bit careful about the words we use as not everyone will have the same associations, and certainly the link between the words we use and the actual rocks and minerals is not at all straightforward.

Another thing worth noting is that wine does contain metal ions, which count as minerals for some people.  Indeed, one can go further and demonstrate that the metal ions found correlate with the vineyards in which they were grown.  Here is one study that has shown that, and I am sure there are more.  But this seems to be a bit of a red herring when it comes to the perception of minerality in wine, as the concentrations of metal ions are so low as to be undetectable, at least at the conscious level.  And if you could detect them you would expect a salty sensation, which is rarely ever reported in wine.  Just under 0.3% of notes in CellarTracker use the words salt, salty or saltiness.  I understand there is some doubt as to how these metal ions get into the wine.  Through the vine roots is certainly one possibility, but another plausible explanation is that it is through dust on the surface of the grapes.  So if this is the cause of minerality in wine, and I doubt it very much, there is a possibility it can be easily manipulated!  Also, before we get too excited by metal ions in wine, and wanting more of them, we should remember that heavy metals (which include some of the minerals in the study linked to above) are poisonous, and a few years ago heavy metals in wine raised health concerns in some quarters.

What minerality means as a tasting descriptor

In this section we move beyond fact, but it is not really opinion either.  It contains assertions – not my assertions, but those I have heard from other people.  Most of them came from online wine forums, and some can be found in the forum links at the top of this post.

Some people seem to use minerality as a general class, implying that with experience and discrimination different types of minerality within the class can be identified.  I think the types of minerality within the class are implicitly specific rock types, but you only rarely see these figuring in tasting notes. Often, however, minerality itself, rather than as a general class, seems to mean something specific to tasters .  But that specific something varies a lot from person to person.

For some it is more of a texture than a smell or taste.  I find it easy to relate to that idea.  Some wines have a chalky texture, which I would attribute to a type of astringency.

Some compare minerality to sucking pebbles, which seems to me to imply a taste or tactile sensation rather than aroma, though you can get minerality on the nose as well.  Others claim to get a taste from licking rocks that is akin to minerality in wine.  I think that must be due to surface contamination or synaesthesia as mentioned above.

The taste of iron is another thing often referred to when discussing minerality.  This seems to be a real phenomenon, mentioned above in the context of metallic smells (see the link in that bit), but it seems to me to be unrelated to other types and explanations of minerality.  Perhaps iron would be a more straightforward descriptor.

A specific example of minerality is flint, often used to characterise Pouilly Fumé.  More correctly it is gunflint, or struck flint, that is associated with the wine, and that predominantly has the smell of sulphur, also technically a mineral.  That brings me on to the theory espoused by some, that minerality in wine is mainly due to reductive sulphur-like odours.  I am not sure how much evidence there is for this, but it is certainly an interesting idea.  The sulphur explanation certainly seems to be a better explanation for the gunflint character of Pouilly Fumé than bits of flint in the vineyard.

Then there are the fanciful descriptions of minerality like “a stream running over wet pebbles”, or “rocks at the seaside”, or “hot rocks in the desert”.  I can relate to some of those ideas, but would hesitate to use them as examples of minerality – I have never inhaled country smells and thought I was sensing minerality.  I also rarely, if ever, get those impressions on a wine – but maybe that is just me.

Others are convinced that minerality is an obvious and well-defined property of a wine – one that is even more obvious than acidity for example.  I find that very difficult to accept.  Acidity can be measured scientifically and that measurement correlates, albeit imperfectly, with our perceptions.  The same can be said of many other descriptors used in winetasting, like the various fruit aromas for example.  But minerality has no clear physical or chemical basis as far as I know.

In some cases people say they can taste slate or chalk because the vines grew in terroir comprising that rock.  I am never quite sure what they mean by that.  Is it that they literally think the wine tastes of slate, or is it rather that it tastes like other wines derived from vines grown in slate?  I am not even sure they always care to distinguish between the two.

How I might describe minerality

The concept of minerality is not something I particularly relate to, and I use it only rarely in tasting notes when I think I can identify something of the nature that other people talk and write of.  So, assuming that I do not have an inability to smell and taste minerality, I started to wonder how I describe what other people call minerality.

Looking at the list of wines that are supposed to show good minerality, the first thing that springs to mind is acidity.  Now I know many say acidity is very different, but nevertheless the correlation between the two seems strong.  I am wondering if some are reluctant to say a wine is acidic because that sounds negative, so minerality is almost a euphemism.

Another thing I was wondering about was whether minerality describes a wine that lacks of other things, namely fruit, but which is still good and fresh, and has subtle qualities that are difficult to describe.  In these case I would probably comment on the lack of fruit or say the wine was lean or austere, but otherwise give the wine a good score.

I also tend to describe some good wines as angular, edgy, or having hard edges.  I see wines more in these geometrical terms, than in terms of minerality, but I suspect the two are related.

Well-delineated is another possibility.  For me this is a very positive term, and a sign of real class.  Cheap wines are often soupy, in my terminology, where all the flavours merge into each other. Well-delineated wines have a few, or several, very distinct flavours.

To the extent that it is true that minerality is caused by sulphur-like odours, the chances are that I would condemn them as sulphurous, rubbery or reductive.  I think I am quite sensitive to these odours and usually find them quite unpleasant – I object to them a lot more readily than other tasters.

Note that I am not claiming my terms are any better than minerality.  Indeed, I am a little embarrassed by some of them, but they are meaningful to me.  Am I getting at all close to understanding minerality, I wonder?


You can doubtless detect a strong note of scepticism here, and I am indeed sceptical.  But more important than my scepticism, is my overall observation that people mean very different things by the term minerality.  So even if the term is meaningful to an individual, it serves little purpose when used in a tasting note designed to communicate an impression of the wine.  Writer and reader may feel that communication is taking place, but often they will be wrong.  If you don’t want communication, but think of tasting notes as a prose art form, that is of course a different matter, and I will leave to your own literary devices.

I must also admit that sometimes my scepticism slips into cynicism.  I don’t doubt that many tasting notes are well-intentioned, and their writers are earnestly trying to express their perceptions, but equally I fear there are unfortunately a lot of pseuds in the wine world, and those who are out there to follow fashion, impress, and sell.

As with many other vinous issues, my mission with minerality is to understand the earnest and well-intentioned – and to flush out the pseuds and quacks.  I also don’t want to rush to judge in particular instances, and definitely don’t want to upset the good guys.  If you have made it to the end of this post, you are definitely a good guy, and have nothing to fear 🙂


It seem that these days the biggest compliment you can pay a wine is to say that it expresses the terroir well, or it is very terroir-transparent.  At least I presume it is a compliment, as you tend not to hear it about wines made from grapes grown in rubbish vineyards.  Using it of course implies that the reviewer is fully au fait with the terroir of the wine in front of him – not only is he capable of recognising its terroir, but also of discerning the degree to which it is expressed.

If only today’s reviewers had been at the Judgement of Paris, there obviously would have been none of that nonsense about confusing the wines from Bordeaux and California.