5.7" Silvery Druzy Quartz Cluster - Uruguay
This is a specimen of a silver colored, quartz cluster from the amethyst mines near Artigas, Uruguay. It was mined from within a pocket in the basalt. The quartz is actually colorless and it is the dark matrix beneath that gives it the appearance of being a silver-black color.
Silicon Dioxide, also known as SiO2 or Quartz, is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich, hot watery solutions called hydrothermal environments, at temperatures between 100°C and 450°C, and usually under very high pressure. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountains forming, and can be hundreds of millions of years old.