4.2" Polished Blue Lace Agate Section - Sanje, Malawi
This is a polished section of blue lace agate collected from Sanje, Malawi. The "face" of this specimen has been polished while the opposite end has been left rough. The blue coloration of this specimen is truly wonderful and vibrant. These chalcedony veins are formed by hydrothermal deposition within large cracks in rock.
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.
Agate is a variety of microcrystalline quartz that displays translucence and in some cases banding. Agate primarily forms when silica-rich fluids fill pockets within rock and/or fossils, resulting in deposition of the silica along the walls of the rock. This process can result in banding patterns as the composition and impurities of the fluids change over time. These banding patterns can either form as flat layers or rounded layers, depending on the surfaces available for deposition.