1. The resulting intergrowth of the two feldspars is called perthite . 2. The intergrowths in perthite have a great variety of shapes. 3. Perthite feldspar within a pegmatite often shows gigantic perthitic texture visible to the naked eye.4. Alkali feldspar dominates, commonly represented by orthoclase and the exsolved lamellar albite, form perthite . 5. Perthite is typical of many granites.6. This is mostly made from fine grained quartz and Perthite , but is coloured red yellow and brown. 7. The largest documented single crystal of perthite was found in Hugo Mine in South Dakota and measured about x x. 8. Perthite is an intergrowth of alkali feldspar of intermediate composition : the coarseness of perthitic intergrowths is related to cooling rate.9. In the acid rocks the common feldspars are orthoclase, perthite , microcline, and oligoclase all having much silica and alkalis. 10. The alkaline feldspar is not potassic, but generally sodic-potassic, which is characterized by interlocking anorthoclase, called perthite .
