Druzy is also spelled or referred to as drusy, druze or druse. It refers to multiple sets of crystals that form on another stone. This occurs from water flowing over a stone for many thousands, or millions, of years. Sediment and silica are left behind as the water evaporates and cools.
The tiny crystal structures cluster together on the gemstone, within a cavity of a stone or geode. The crystals are often too small to see with the naked eye, but when they join together, each refracts and redirects natural light. This creates a shiny surface of dancing light that often looks like a sugary coating.
Some druzy crystals are larger and more pronounced. This does not always indicate that the crystals are older. Instead, they likely existed in an area that provided a better supply of the silica and sediment needed to develop longer, stronger crystals.
Druzy can happen on any type of stone or mineral. It is most common on quartz because quartz collects silica easily. The other common “host” for these crystals is agate, but you can also find it on other mineral specimens that can support the growth of the tiny sparkling crystals.
The druzy crystals are clear so they reflect the color of the stone beneath them. That means druzy stones can come in just about any color.