Are those little pieces of glass? Okay, its definitely not glass, but what are those crystals adhering to the cork? Tartrates… huh? Never heard of ‘em, are they dangerous? Do they affect the wine? This battery of questions follows shortly after yanking a discolored cork, encrusted with beautiful salt-like barnacles of a wine you are planning on serving. They are appropriate (but unfounded) concerns and it suggests you are paying attention. While it is true that it can be a unnerving the first time you spy the formations dwelling contentedly on the end of a stopper, let me guarantee you that it is a cooler experience than a scarier one.

So what are they? The formations are potassium acid tartrates that have precipitated out of the wine, nesting on the sides and bottom of the bottle and cork. Some casual wine drinkers will go an entire lifetime without seeing them so I like to think of tartrates positively, sharing the experience with the people around me, with the nerdy enthusiasm of an amateur astronomer viewing a meteor shower on the sands of Anita street beach with my first girlfriend.

They are most commonly found on aged bottles but can also be detected in the process of fermentation. Tartrates come directly from tartaric acid; the crystals that appear at the end of the cork are actually the potassium salt but they are a result of the sediment from the bottle in the form of lees (dead yeast cells—the same thing that makes wine soooo creamy), pulp and tannins.

The next time you encounter tartrates please do not be alarmed; try instead to embrace the glasslike chards glued to the cork of your aged seven fifty of Riesling, knowing that they are a natural phenomenon in wine.