Development of Perthite in the Topaz Bearing Degana Granite, Rajasthan

Perthites are important disequilibrium textures found in the topaz bearing Degana Granites. Out of the two types of the perthites in the Degana Granite, the Fine-Grained stringlet type perthite is found in the unaltered portion while the dominant coarser type replacement perthite is present in the potassic alteration zones. In the present communication, a schematic model for the progressive evolution of perthite texture in the potassic alteration zone of the Degana Granite is proposed.