This Specimen has been sold.
3.8" Silvery Quartz Cluster With Calcite - Uruguay
This is a specimen of a silver colored, quartz cluster with a calcite crystal inclusion, 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. The calcite is the large crystal. Comes with a removable wood stand for display. The edges of this cluster have been polished to reveal the stunning deep mineral formations.
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.