As a kid, I used to go hiking in the Cascades, and one of my favorite memories was drinking water straight from the streams. Not only did it have a sweetness and a gorgeous, mouth-filling roundness, but it also had this flavor and slightly granular texture that suggested the eroded pebbles and stones over which it was flowing. This was my first exposure to what I now think of as "minerality." And I'm sure my love of mountain water pushed me in some way to pursue wine, especially mineral wines, which, it turns out, are a somewhat controversial subject in the wine world.
Why are they controversial? Because wine writers and scientists are at odds over what minerality actually means. English wine journalist Jancis Robinson says in this article: "Anyone who has visited the volcanic island of Santorini ... [i]t is not surprising that fine wines made here taste intensely of the volcanic rocky soil."
Meanwhile, scientists like UK geology professor Alex Maltman contradict that: "whatever 'minerality' in wine is, it is not the taste of vineyard minerals."
Do the wines of Santorini really taste like volcanic rocky soil? Not exactly. Nevertheless, there is something in the wines that suggests stoniness and dissolved minerals. Everyone can pick it up, expert tasters like Robinson and novices alike. Can the common sensory detection of millions of people be wrong?
I think not. It's just that what we call minerality may not be minerals. As Terry Theise, the celebrated importer of European wines, put it in his recent book, Reading Between the Wines: "We don't care whether the flavor we call mineral results from an actual trace of dissolved literal mineral in the wine. I personally think it doesn't. More accurately, I'm agnostic on the question, because it hasn't (yet?) been demonstrated to be true. But something is creating that definite, tangible flavor, and we don't know what or how."
Clark Smith, a scientifically minded winemaker and writer based in Sonoma County, California, has offered a few interesting theories as to what might cause the sensations we describe as minerality. They include the idea of an electron discharge that creates the almost electric buzz that some mineral wines provide, as well as speculation on sulfides—sulfur-bearing compounds released by the action of yeasts during fermentation—that may perhaps give a stony texture and flinty aroma. (I'm partial to the latter theory.)
Either way, according to Smith's ideas, "mineral" wines may emanate from rocky, mineral-rich, nutrient-deficient soils—the kinds that are especially abundant in the Old World, where soils have been depleted over thousands of years of constant farming, and where grape vines were historically relegated to poorer, rocky soils. Neither is much true of most new-world vineyards, perhaps accounting for the trope that old-world wines are more mineral than new. It's one reason why we prize French classics like Chablis, Sancerre, Côte-Rôtie, Vouvray, Puligny-Montrachet; German Rieslings from the Mosel and Rheingau; and Italian Nebbiolos and Verdicchios.
As eloquently put by Theise, minerality is a metaphor: "I think minerality is perhaps the noblest of flavors because it is metaphorical, and metaphors work on the imagination. Fruitiness, on the other hand, is a simple matter of identification—it tastes like this apple or that pear, this peach or that melon—and once you've identified it, you don't think anymore. Minerality in contrast is suggestive, even mysterious. We don't know what it is or how it got there. We grow alert to the loveliness of the unknowable."
And the unknowable, even to a boy of six drinking from a mountain stream, is the most alluring taste of all.