Vug

 ( Petrology ) 

A vug, vugh, or vugg () is a small- to medium-sized cavity inside rock. It may be formed through a variety of processes. Most commonly, cracks and opened by tectonics activity (folding and faulting) are partially filled by quartz, calcite, and other secondary . Open spaces within formed by an ancient collapse are another important source of vugs.

Vugs may also form when mineral or inside a rock matrix are later removed through erosion or solvation processes, leaving behind irregular voids. The inner surfaces of such vugs are often coated with a crystal druse. Fine crystals are often found in vugs where the open space allows the free development of external crystal form.

The term vug is not applied to veins and fissures that have become completely filled, but may be applied to any small cavities within such veins. are a vug-formed rock, although that term is usually reserved for more rounded crystal-lined cavities in and ancient . Geology Buzz: Vug

The word vug was introduced to the English language by Cornwall Mining, from the days when Cornwall was a major supplier of tin. The history of Cornwall, civil, military, religious, ... (Page 56), Richard Polwhele - 1816 The Cornish language word was vooga, which meant "cave".

• Amygdule
• Rock microstructure
• Vesicular texture