5.1" 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. This specimen comes from Hardangervidda, Norway and comes with an acrylic display stand.
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.