This Specimen has been sold.
2.6" Quartz, Anatase and Adularia Crystal Association - Norway
This is a beautiful association of quartz crystals, anatase crystals and white adularia (variety of orthoclase) on a schist matrix. The anatase crystals are small and can be found clinging to one edge of the matrix. This specimen comes from Hardangervidda, Norway.
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.
Adularia is a variety of feldspar that had the chemical formula KAlSi3O8. It's found most often as colorless to white aggregations within metamorphic rock, with one example being formation within cavities of crystalline schists. The crystals are commonly twinned, glassy and prismatic in structure, and in some cases they display opalescent characteristics. Adularia is very similar to orthoclase, even baring the same chemical formula, however it has a different crystalline structure and reacts differently to various tests.
Anatase is composed of titanium dioxide, and typically forms dipyramidal crystals, although variations can occur with mineral clumping. Four pointed X-shaped anatase crystals, while rare, have been found and are known as "X-shaped penetration twins". Horizontal striations can be seen across most anatase mineral faces, with most crystals ending in points, or with variations of flattening on each end.