One of the most controversial concepts in the world of wine is "terroir." Terroir is a French term that can be taken to mean everything from soil typology to mystical "somewhereness," but is best described as a combination of geographical factors and microclimate affecting the growing of grapes for wine. Very often cultural practices in winemaking are blanketed under the term terroir as well, and even more often the term is used to denote the typicity of a wine from a specific region such as Burgundy or Bordeaux (the degree to which the wine reflects the signature characteristics of the grapes used to make it).
The debate gets a bit dicey and there are many camps: some subscribe to a scientific outlook while others employ near-religious ideologies in winemaking. The word terroir can also be used to distinguish "Old World" wines made in France or Italy from "New World" wines from regions such as California or Australia, and in that sense the word invokes a certain special status as crafted versus mass-marketed wine.
Minerality is often heralded as the keystone of terroir. For a wine to have a taste of wet stones or slate is considered proof positive of terroir (and yes these are considered positive traits), although this may correspond to a range of factors from sulphur compounds to acids present in the wine. One prime example is Chablis, a Chardonnay-based white wine from Burgundy, France. Often thought to possess an aroma of oyster shells, Chablis is grown over argilo-calcaire soil that is laden with fossilized oyster shells.
So what does terroir have to do with cocktails? "Provenance" is a much better term for the typicity of a drink, but the use of minerals in cocktails constitutes a kind of "cocktail terroir," if you will.
The most literal interpretation is adding minerals directly to the cocktail. According to a recent article in the New York Times, Italian bartender Christina Bini is actually adding rocks to her Martinis at a new restaurant in New York called Il Matto:
They come in two varieties, one ballasted by a white stone from the Liguria region in northwest Italy; the other with a black stone from Mongolia. All the stones are soaked in vermouth for at least 12 hours before they are deposited in their drinks, resulting in an extremely dry and extremely eccentric martini.
This is very similar to experiments taken on by wine maverick Randall Grahm, who created Bonny Doon wines. Grahm once added stones to his wines in an attempt to replicate terroir.
The more common application of minerals in cocktails is through water, both bottled waters and ice. When I started using Apollonaris water in the Gin Rickey, the original water used in Washington, D.C.'s native cocktail, I recognized immediately the improvement—the minerals from this water add depth to the drink above and beyond club soda. I suggest keeping a few different bottled waters, such as Apollonaris and club soda, on hand.
In addition to mineral water added directly to the drink, using mineral waters to make ice can either express or dull aspects of the flavor in a cocktail. This may not lead one to discern the actual taste of the water in a cocktail, but you can certainly tell whether the other flavors in the drink are focused or "muddy."
Does it then follow that you should use different water for ice depending on the cocktail? Yes and no. For ice I try to stick with something that is flavor-neutral for my drinks, and stay away from tap water, where the predominating chemical is chlorine. Filtration is essential, and the ice should be clear. I know that many bartenders have used Fiji water to freeze ice, and Saratoga has worked well for me. Other than that, it's an area worthy of experimentation. Perhaps it's time for us to become cocktail terroirists?