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Andrew Alden

Naïve Minerality

By October 26, 2009

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Winemakers and wine reviewers are notorious for ladling on the descriptive words. James Thurber skewered the excesses long ago in a cartoon that featured a sophisticate saying, "It's a naïve domestic burgundy without any breeding, but I think you'll be amused by its presumption." And everyone tastes wine differently, even the same person on different days. But all that said, wine evaluation is a pretty rigorous process with a strict vocabulary. The glaring exception is the set of flavor elements recently lumped under the word "minerality."

None of us has a problem dealing with a wine with "cherry notes" or "silky tannins." No one thinks that actual cherries or silk are involved, just flavors or perceptions that resemble them in some way. But ever since "minerality" came into vogue, the notion that, say, a vineyard set in slate bedrock yields wine with a "slaty" taste has persisted in some circles. In a session at the 2009 GSA Annual Meeting dedicated to terroir, geologist Alex Maltman told us that "mineral" wines, before the 1990s, used to be described as "lean" or "austere." That basically means "not especially sweet, fruity or aromatic." So I think that "mineral" is an advance because it allows us to note the presence of flavor elements from the mineral kingdom like soil, chalk, wet pavement, dust and other evocative scents, not just note the absence of the usual wine flavors.

The mistake is in thinking that wine corresponds directly in flavor to the ground it's grown in. Chalky soils don't yield wines that taste of chalk, thank goodness. It shouldn't take much effort to separate "minerality" from minerals the same way we separate "fruitiness" from actual fruit. But as I listened to Maltman demolishing naïve "minerality," I found myself wondering about the real smells of real rocks. Limestones and cherts often have interesting smells, but I don't think they're trustworthy guides for rockhounds. Maybe they're just smells of soil fungi or something else unrelated to mineralogy.

Do any of you use smell in the field?

UPDATE: One news story about the session was misleadingly headlined "Geologists debunk soil impact on wine." Blogger Dr. Vino followed up with a more substantive entry on the GSA session on terroir.


October 26, 2009 at 6:50 pm
(1) Lockwood says:

I can often tell I’m near a sulfide occurrence, if the weather is warm and damp to wet, from the sulfur odor. The most interesting one I’ve used is arsenopyrite, which, upon being broken, has a distinct oniony to garlicky odor. Petroleum odors are also very distinct with tar sands and oil shale, but I’ve never used those, just noticed them in samples.

October 27, 2009 at 3:24 am
(2) Jack Lynn says:

A noted smell in field surveying operations before the world of seismic, was the term “petroliferous”. Some sed. rock sample, especially limestones and dolomites in surface exposure can have a residual odor of petroleum when broken open, which was emplaced after deposition, and before erosion exposure. This is very true of some Ls in the West Texas area around Alpine, where I went to school.

October 30, 2009 at 2:43 am
(3) Chris Scott says:

I’m in the wine trade, many people think that the likely cause of a mineral aroma in the wine is developed from reductive wine making. That is winemaking without oxygen present. The aromas are therefore part of sulphur chemistry.

October 30, 2009 at 9:36 pm
(4) Howard says:

I don’t know good wine from bad kool-aid, but as a wellsite geologist, I absolutely use smell in the field: I always give my samples a sniff while I’m washing them, as it’s usually the first indication that I need to look for oil staining. Native sulphur co-occurs with anhydrite in some areas, so heating samples (which I no longer do) to dry them and catching a whiff of sulphur would often be a good first indicator of an anhydrite zone.

November 2, 2009 at 10:31 am
(5) Karen says:

I love wine and I have heard wine reps describe the terroir of each bottling many times. I was driving north on Hwy 5 through Stockton to Sacramento the other day and could not help wondering how those hundreds of acres of vines were faring right next to those hundreds of acres of cow and dairy farming. The methane smell is obnoxious and the soil and underlying water table/springs must be experiencing this overload. As for minerals and all the variables-it seems like a life long chemistry experiment.

November 2, 2009 at 1:18 pm
(6) Bev says:

You can tell if there is clay/silt in a “dirty” sandstone by the “earthy” smell when wet. Breathe on the rock and then sniff. Pure sandstones don’t smell like much, but dirty ones smell of earth.

November 3, 2009 at 5:09 pm
(7) Pete Modreski says:

I have never claimed to be a wine snob, to say the least (i.e., I must admit to an “uneducated palate”), and I have often heard with admiration, wonder and skepticism, the remarkable variety of fruits, roots, nuts, and berries that connoisseurs claim to taste in wines–much less, “minerality”. As to the smell of rocks and soil, I also have always been impressed by that “earthy” smell of clay-bearing rocks and sediment, especially when moistened, and I’ve wondered about what really causes it. I often have students experience this, blindfolded, when I’m asking them to use all their senses to explore what they can tell about a rock or mineral. A few years ago I exchanged some emails with a British research who had published a paper in (Nature?) about gases and smells associated with clays and soil and what this tells about interactions between organic compounds and clays, perhaps even relating to the role clay minerals may have played in the origin of life. But I still never have gotten any clear insight into exactly how a totally nonvolatile silicate mineral (clay) can release “something” to produce an earthy smell when our moist breath hits it!

November 5, 2009 at 11:55 pm
(8) Leslie says:

One of the distinctive things about my favorite mineral, sphalerite, is its unmistakeable odor of sulfur. Sometimes difficult to identify, the smell always clinches it for me. And although it’s not wine, the taste of fresh spinach always has a very earthy soil flavor to me (and not because I haven’t washed it well). :-)

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