Alex Maltman - All Comments

RE: Musings on Minerals and Metaphors

Diana Khandilyan — Thu, 25 Sep 2025 19:43:02 GMT

As a geophysicist, I fully understand that vine roots cannot dissolve and absorb minerals directly, and that what we taste in wine is not literally the slate, chalk, or granite of the vineyard. But there is something deeply romantic in that notion. Geologists and geoscientists, after all, are romantics at heart—we spend our lives reading stories in rocks. So even if “minerality” is metaphorical, we’d like to keep tasting it—especially the volcanic soils of my homeland, Armenia, in the glass of high elevation Areni. Cheers. Diana

RE: Musings on Minerals and Metaphors

Daniel Webber — Sun, 08 Jun 2025 20:24:18 GMT

Awesome read!

RE: Part 2: Vineyard Geology

Christopher John — Tue, 13 May 2014 23:54:21 GMT

Since the soils are so diverse in Alsace would grés de Vosges be a specific greywacke soil?

RE: Part 1: Soil Principles

Christopher John — Tue, 13 May 2014 22:25:39 GMT

"Much of the root skeleton becomes established in the first few years of growth although small “feeder” roots continue to grow"

Would this make field grafting rather bench grafting more advantageous overall? Particularly in the vines ability to build a network for water and nutrient absorption.

RE: Part 1: Soil Principles

Admin — Fri, 25 Jan 2013 22:58:04 GMT

There is an interesting term called Petrichor which is the smell of rocks when they are wet. Turns out the smell is not from the rocks but from plant base oil residue on the rocks. Maybe the smell is coming from chemical plant based residue native to the area? See the Wikipedia entry:

en.wikipedia.org/.../Petrichor

RE: Part 1: Soil Principles

Ed Hodson — Fri, 25 Jan 2013 20:58:44 GMT

More on the eucalyptus notes sometimes found in reds: The culprit is thought to be an aromatic compound called 1,8 cineole, and one of the reasons you find it in vineyards proximate to eucalyptus groves is that the eucalyptus leaves end up being harvested with the grapes as "MOG" (Material Other than Grapes) when grape rows close to the groves are mechanically harvested! www.wine-searcher.com/.../eucalyptus-in-australian-red-wines

Concerning the smell of rocks, here's something to consider: While DRY rocks have little to no aroma, WET ones sometimes do. Wet chalk certainly does. Same's true for some minerals when you ignite them, sulfur being an obvious example. And those aromas lodge in our memories, our olfactory aroma banks if you will.

So for what it's worth, I believe when we smell something in the glass that reminds us of the smell of a particular rock, that's possibly some sort of triggered response to an olfactory cue coming not necessarily from presence of the rock/mineral itself, but from some compound that behaves like or has something in common with our memory of what the wet/warmed/ignited rock smells like, just like when our noses think we're smelling green bell peppers in wine, we're actually smelling 3-isobutyl-2-methoxy-pyrazine (IBMP), not a bell pepper infusion. Like Alex said so well above, "We all accept that, say, plummy or spicy wines don’t contain plums or have had spice added so why do rocks and minerals have to be treated differently? Despite the Burgundian legacy, perceived tastes of minerals and rocks have to be metaphorical." Agree wholeheartedly.

Great article, great thread!

RE: Part 1: Soil Principles

Rose Mitchell — Fri, 25 Jan 2013 18:58:33 GMT

Wonderful article as well as comments. Whether a novice or expert when it comes to understanding the influences of soil composition and its direct influence on grape flavors this certainly sets the gears in motion.

RE: Part 1: Soil Principles

Admin — Fri, 25 Jan 2013 18:03:46 GMT

Back to the comment about the "smell" of chalk. It seems that calcium sulfate is also odorless. Any idea what smell I am thinking if when I imagine blackboard chalk from school???

RE: Part 1: Soil Principles

Jared Fischer — Thu, 24 Jan 2013 10:41:02 GMT

Problem #2 solved by digging deeper into the files page, now I just wish I could delete my previous two comments. Here's the link again: www.guildsomm.com/.../sur-la-min_E900_ralit_E900_-dans-la-d_E900_gustation-des-vins.pdf.aspx

RE: Part 1: Soil Principles

Admin User — Wed, 23 Jan 2013 21:30:13 GMT

Additional food for thought: when a lot of us imagine the smell of chalk, we are thinking about blackboard chalk.

Blackboard chalk is usually gypsum, a form of calcium sulfate, rather than calcium carbonate. Perhaps we are smelling a sulfur compound here?

RE: Part 1: Soil Principles

Anonymous — Tue, 22 Jan 2013 17:54:15 GMT

Great read! Looking forward to the next installment!

RE: Part 1: Soil Principles

Admin User — Tue, 22 Jan 2013 16:30:55 GMT

Thank you Alex for addressing some of these comments. We are looking forward to the second installment!

RE: Part 1: Soil Principles

Alex Maltman — Tue, 22 Jan 2013 14:41:52 GMT

Thank you all, for your observations and questions. I hope the following is helpful.

Geoff: I wish I could reveal some data on why Chablis tastes like it does, but I’m afraid I can’t! Almost certainly its unique taste is due to the particular organic compounds developed during vinification from that region’s juice precursors. While impressive progress has been made in recent years relating such compounds to grape varietals, there are few data, so far as I’m aware, attempting to explain the typicity of wines from particular areas and none for Chablis.

I would argue that a list of factors determining the compounds at Chablis would be headed by those deriving from the local, high-latitude climate, then from aspects of the viticulture and vinification, with any influences from the soil way on down the list. (It pains me, as a geologist, to say that but I have to be guided by the evidence.) Time may tell. In other words: “no”, science doesn’t as yet know exactly why Chablis has its unique flavor.

But just to provoke more thought: it’s your “chalk-like” remark that I struggle with. Obviously it’s a valuable tasting cue for you, and for others, but chalk (calcium carbonate) is tasteless and odorless. However, some chalk is powdery to the touch so perhaps you are referring to something to do with mouthfeel rather than flavor?

Incidentally, there is no geological chalk at Chablis; neither is there flint, another tasting comparison that is often made for Chablis. Also, among the frequent marine allusions (perhaps because enthusiasts are aware that the geology at Chablis happens to be a sedimentary rock laid down under the sea, as explained in the second of my articles), iodine is often mentioned and related to the local soil. Such as in “the hallmark of great Chablis is the distinct iodine note, coming from the iodine-rich Kimmeridgian bedrock” and “How else can you explain the iodized notes in Chablis if not by the composition of its soil?”. I have recently been involved in a project analysing the iodine content of the soils, vine-tissues and wines of Chablis and nearby areas (and elsewhere). To cut a long story short, it turns out there is actually, on average, less iodine at Chablis (only around 4 microg/L) than in Burgundy soils, vines and Chardonnays, and a lot less than in the Australian and Argentinian examples we measured.

So these geological phrases – such as your “chalk-like” – have to be metaphors, thought associations, helpful personal cues, etc., but not an articulation of anything that’s actually in the wine.

Regarding Shayn’s baby steps, you won’t be surprised that as a scientist I would stick with an established science-based tasting scheme. Ron Jackson’s 2009 book is definitive (Wine Tasting, a Professional Handbook, 2nd edn., Burlington, Massachusetts: Academic Press) and the Noble et al. aroma wheel (originally in the 1987 American Journal of Enology and Viticulture) is well established and widely reproduced. For mouthfeel, Gawel et al.’s wheel is now available at www.winepros.com.au/.../mouthfeel.pdf

But my main point in all this is a plea not to single out tasting terms that involve geology (slate, flint, mineral, etc.) to have a literal meaning. We all accept that, say, plummy or spicy wines don’t contain plums or have had spice added so why do rocks and minerals have to be treated differently? Despite the Burgundian legacy, perceived tastes of minerals and rocks have to be metaphorical.

Justin’s input regarding marijuana is very interesting, In fact I’ve thought along similar lines with the taste of my greenhouse tomatoes! But subjective impressions are one thing, and very influenced by any prior knowledge: I don’t know how well this would hold up to proper testing. And there’s a major difficulty in extrapolating this idea to wine. Here we’re not just talking about the flavor of the vine leaves or the fresh grapes, but about the end result of extensive processing, and we know it is in this that the bulk of wine flavor compounds are produced.

Regarding Geoff’s and Jason’s question on bottled waters, I understand there’s a whole other debate out there about what such waters may or may not taste of. But putting that aside, the pertinent point here is that in comparison with wine the concentration of inorganic solutes in commercial waters is far greater, more varied and very different in origin.

I only have data for European waters. As a few examples, unlike wine, bottled waters can contain significant (up to 0.5 g/L) of tasteable anions such as sulfate. And while the calcium content in wines doesn’t differ a great deal from around 65 mg/L, some bottled waters have as little as 9 mg/L whereas some exceed 500 mg/L (with a taste threshold in water of 130 mg/L). The copper content of wine typically averages around 1.5 microg/L but in waters reaches over 19 microg/L (with a taste threshold in water of 6 mg/L). Please note that these “taste” thresholds are merely detection and not identification values, and that they’re in pure water, where obviously there’s none of the powerful aromatic volatiles of wine. These contrasts with wine come about because the inorganic solutes in groundwater have been dissolved over very long residence times directly from the host aquifer.

Stephen: rocks have no smell, and although any associated organic material may have odor, there is no known way of transmitting it through vine roots into grape juice. However, aerial matter landing on vine stems and grapes is an entirely different situation. For example, there is good documentation about agrochemicals, contaminants from traffic, odor compounds from forest fires, etc. landing on stems and berry skins, then directly dissolving in the must.

So Kevin: while there are various obstacles (of grain size, insolubility, lack of distinctiveness, flavor, etc.) to your Chablis/minerality idea, your eucalyptus point is well taken. We are highly sensitive to the main aromatic volatile in eucalyptus (as little as 1 microg/L) and it is demonstrably present in some California wines at >20 microg/L. But, significantly, only in reds, because of their maceration allowing dissolution from the grape skins. So there’s little doubt that skins are the source. Moreover, the concentrations in Australian Shiraz (also up to 20 microg/L) have been shown to vary with proximity of the vines to eucalyptus trees!

Oops, sorry about the Snipes Mountain mistake. My fault. Thanks, Beth.

Jack: I have no data on vineyard soil/wine pH relationships but I corroborate Matt’s remark that the anecdotes are inconsistent. It may be worth mentioning that an additional complication is that the mineral framework of soils and the parent bedrock, being solids, themselves have no pH (which is free hydrogen in solution). Their acidity/alkalinity has an entirely different basis. Granite, for example, is termed acid because it has a high silica content. Noone said this was straightforward!

RE: Part 1: Soil Principles

Kevin Arndt — Tue, 22 Jan 2013 07:16:00 GMT

I have to agree with Stephen on this one. Many Australian Shiraz smell of eucalyptus to me. I have always attributed this to pollens settling upon the grape skin and being absorbed into the grape. I know the waxy skin should protect the grape but I feel that it is incorporated into the flavor of the wine. Could the 'minerality' we associate with specific regions (Chablis seems the one most commented upon) be a result of the soil being blown into the air and settling upon the grape skin? In this case limestone and chalk dust settling upon the grape and being absorbed into the must.

RE: Part 1: Soil Principles

Admin User — Sun, 20 Jan 2013 16:38:36 GMT

Some good additional reading on the subject: www.enologyinternational.com/.../Minerality_reprint.pdf