Wine producers like to kneel in their vineyards and scoop up a handful of dirt for you to admire. "See this gneiss (or schist, or limestone)?" they'll say. "Minerality. You can taste it in the wine."

We wine geeks obligingly do, prizing it above fruit, oak and tannins together. It's a classy quality, associated with the superior vineyards of Europe, where restraint and elegance rule. It suggests a lovely feeling of somewhereness, separating manufactured, branded wines from true wines of place.

The only problem is . . . it's completely bogus.

In human taste, psychology often overrides physiology. Few of us who enthuse about slaty freshness and chalky austerity have tasted the rocks in question, not since the third- grade bully filled our mouth with a blackboard eraser. Our well water is full of minerals that form hard, gray stalactites on the shower head. But it tastes nothing like our favorite wine.

So what does the "minerality" we rave about taste like? Like the damp walls of a gothic cathedral. Like Alka-Seltzer and club soda. Like a still, hot day with air so heavy you want to unzip your skin and crawl out, when suddenly the sky cracks and giant raindrops begin pounding puffs of dirt out of the road while steam rises from surrounding rocks.

But this is not the taste of minerals absorbed by the roots of the vine. Minerals are essential nutrients. Plants don't just put them on an elevator and push "up." They must metabolize them to grow, or fruit would taste like dirt.

Not that soil doesn't make a difference. Side-by-side vineyards in different geology can yield very distinct wine. But the difference is in fruit, body and complexity, not "minerality."

If minerals don't cause "minerality," what does? Hard to answer, since it's not an objective, analytical concept with reference compounds to define it. Unlike wet dog, soy sauce and geranium, minerality has no official description and doesn't appear on the UC Davis Aroma Wheel. Probably the culprit is yeasts, which, while turning sugar to alcohol, free the aromatic chemicals that distinguish wine from boozy grape juice. A certain organic sulfur molecule redolent of flint, for example, or the phenols responsible for the earthy funk of the Southern Rhone.

(A subtle quality, minerality gets lost in the lushness of New World fruit. It's easier to perceive in Europe, where grapes don't get as ripe as ours. Which, you could argue, makes their vineyards worse than ours.)

If minerality can be produced in the winery - as it no doubt already is in some giant lab in New Jersey that makes fabric softener - then it's no longer the purview of scarce old vineyards, and we can have more of it. But as it turns out, the flavor means nothing without the idea. Wine lovers want the mystic sense of going on a psychic journey through a liquid medium unique to certain rocks and crags.

Old World producers like to pretend their wine makes itself - there wasn't a word for winemaker until Aussies and Yanks invented it. Never mind that many of these gentle custodians of nature, those handers of brushes to the great artist beneath their feet, have managed to revamp their product to please wine critic and guru Robert Parker.

This reticence comes from a fundamental Old World/New World difference. While we insist any one of us could grow up to get crushed in the New Hampshire primary, Europe holds a deep, if unspoken, belief in rank, class and nobility.

And the feudal days were all about owning land. Maybe anyone today can go to school and become a winemaker, but only the chosen few can bequeath priceless real estate to their heirs. The real role of minerality, it seems, is to confer royalty upon a producer. Which is a pretty big job for a little bit of Alka-Seltzer.

jester@corkjester.com

For a taste of minerals, try:

WHITE

* Bodega Huguet de Can Feixes Blanc Seleccio 2006 (Spain) $14

* Goisot Borgogne Aligote 2005 (France) $16

* FX Pichler Riesling Steinertal Smaragd 2005 (Austria) $27

* Grosset Riesling Polish Hill 2005 (Australia) $25

RED

* Red Guitar Navarra Old Vine Tempranillo/Garnacha 2005 (Spain) $10

* Vega Sindoa El Chaparral Garnacha Old Vines 2006 (Spain) $14

* Coudert Fleurie Clos de la Roilette 2005 (France) $16

* Paul Pernot Beaune "Clos au Dessus des Marconnets" Villages Red 2005 (France) $30