This Specimen has been sold.
3.9" Spessartine Garnets & Smoky Quartz on Feldspar - China
Here is a beautiful 3.9" long specimen that contains spessartine garnets and smoky quartz that formed from a bed of feldspar, collected from Fujiang, China. The base of this rock has been cut flat, allowing for aesthetic presentation without the need for a display stand.
Feldspars are a group of rock-forming tectosilicate minerals. It is also one of the most common minerals on earth, making up nearly 60% of the crust.
Silicon Dioxide, also know 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.
Smoky quartz is a grey-brown to black variety of quartz. This common name is derived from from the appearance of smoke within the quartz crystal. Dependent on the location and the chemicals present during formation, smoky quartz can appear opaque black, however it’s typically translucent to some extent. It’s believed that the quartz gains this color from a combination of natural irradiation and aluminum impurities.
Garnets are nesosilicates having the general formula X3Y2(SiO4)3. There are many species of garnet which include pyrope, almandine, spessartine, uvarovite, andradite and grossular (varieties of which are hessonite, cinnamon-stone and tsavorite). Garnets are found in a wide variety of colors including red, orange, yellow, green, purple, brown, blue, black, pink, and colorless, with reddish shades being the most common.