In the lower left, a spherule, or sphere-shaped grain, can be seen penetrating the interior of a small cavity called a vug.

Vugs are small cavities inside rock that are formed when crystals form inside a rock matrix and are later removed through erosive processes, leaving behind voids. A common cause of vugs is minerals precipitating from solution in water, and then later being dissolved again by less saturated water. The inner surfaces of vugs are often coated with some of the mineral matter that formed them. Download high resolution version (817x617, 41 KB)PIA05481: Which Came First? Vug or Spherule? This image, taken by the microscopic imager onboard the Mars Exploration Rover Opportunity, shows a close-up of the region dubbed El Capitan, which lies within the rock outcrop at Meridiani Planum, Mars. ... Download high resolution version (817x617, 41 KB)PIA05481: Which Came First? Vug or Spherule? This image, taken by the microscopic imager onboard the Mars Exploration Rover Opportunity, shows a close-up of the region dubbed El Capitan, which lies within the rock outcrop at Meridiani Planum, Mars. ... Quartz crystal A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ...

Vug is also refers to a Titanian individual in Philip K. Dick's science fiction novel The Game-Players of Titan, ISBN 0679740651. Atmospheric characteristics Pressure 160 kPa Nitrogen 95 percent Methane 5 percent Titan (tye-tun, Greek Τιτάνας) is the largest moon of Saturn and the second largest moon in the solar system, after Jupiters moon Ganymede. ... Philip K. Dick Philip Kindred Dick (December 16, 1928 — March 2, 1982), often known by his initials PKD, and sometimes by the pen name Richard Phillips, was an American science fiction writer and novelist who changed the genre profoundly. ...

VUG is an acronym for Vivendi Universal Games. Vivendi Universal (VU) is a French company active in media and communications with activities in music, television and film, publishing, telecommunications and the Internet. ...