A layer of very fine crystals formed on a semi precious stone chalcedony or agate, is known as "Druse" "Drusy" or "Druzy".
Many agates are hollow, and in such cases the center often consists of quartz crystals growing towards the free space, forming a crystal-lined cavity, or geode. These layers can also form in "vugs" or open pockets left when rock was forming.
Drusy cabochon or Druzy stone are commonly used for any type of semiprecious gemstone cabochon that hasn't been ground down, and has natural crystal formations on top. And there are many man-enhanced varieties on the market too. These are usually natural agate crystal quartz cabochons that are "coated" with a substance such as titanium, which makes a beautiful rainbow infused purple color.
Agate is a type of chalcedony, usually at least slightly translucent and banded or with inclusions. It forms in concentric layers in a wide variety of colors and textures. Each individual agate forms by filling a cavity in host rock. The largest deposits of agates in the world are found in southern Brazil.
Druzy Agate or Druse Agate has a hardness of about 7 on the Moh's scale.
Metaphysical Properties of Druse Agate: Drusy Agates in general are known for being lower intensity stones. They are considered stabilizing and strengthening influences. Drusy stones are said to be helpful in self exploration, patience, and in beginning new projects.