vug

/vʌɡ/
noun
  1. A small cavity or hollow space in a rock, often lined with crystals.
    • The hiker found a beautiful vug filled with quartz crystals inside the limestone.
    • The vug in the granite was empty, but its walls sparkled with tiny pyrite cubes.
    • Geologists often examine vugs to learn about the minerals that formed in the rock.
Synonyms
What does "vug" mean? | whatsthatwordmean | whatsthatwordmean