I've journey to two different apartment complexes and a rental home with the same bottle of cheap white wine in my refrigerator. It was sort of a tradition to bring it with us everywhere we moved.

I felt it was time to enjoy it or pour it down the drain. To my wife's surprise, she saw what looked like sand crystals at base of where it was resting. "EEWW!" she clamored.

Actually, though it visually unappealing, it's harmless. The "crystals" are just naturally ocurring potassium and tartaric acid molecules that solidified.

All it means is that the wine did not go through the cold-stabilization process. This is when the wine is chilled to 30 degF for at least 36 hours; it forces precipitates to gather, clump together then fall to the container vessel. The wine is then racked off those particles then bottled. The process exists so that when the wine makes it to you and toss it in the fridge, these visually unappealing, but harmless particles don't occur in the bottle.

Cold stabilization requires a pretty big and costly operation so not all wineries, especially the smaller guys, can even afford to put their wines through it.