Dazzling Druzy

"A druzy is the term that refers to a blanket of tiny, sparkling crystals often found inside a geode or an agate. The sparkling appearance of druzy (or, more commonly, drusy) is like that of spilled salt or sugar. The formation of the tiny crystals occurs after molten rock begins to quickly cool, trapping gasses within it as it solidifies. The trapped gasses cause crevices and cavities in the cooling rock. Nutrient-rich groundwater later flows through these gaps and crevices, depositing layer after layer of minerals which crystallize on top of each other. The resulting encrustation is called druzy (drusy, druse, druses). This process doesn't take days or weeks, but a few hundred or even a few thousand years." - from eHow.com