Textural Analysis of a Microcrystalline Quartz using X-Ray and Electron Backscatter Diffraction (EBSD) Techniques

An unusual microcrystalline quartz texture has been recognized in the investigation of pervasively silicified ore-bearing horizons occurring in the uppermost part of carbonate platform sequences of different ages (from Precambrian to Mesozoic) and of different geotectonic settings. This peculiar texture has been labeled texture, and derives only by a rather fast and preferred crystallization of quartz on the pre-existing morphological faces of other developed quartz crystals. The 001 pole figures obtained by X-ray textural analysis describe this grid-work texture as constituted by two components of orientation: one component at about 35° from the normal to the surface of the sample and a second orientation component having the c axes oriented at about 75° from the normal to the surface of the sample. Textural maps and parameters obtained by EBSD found very similar components of orientation highlighting as 30-40° and 70-80° misorientations are very common; moreover they allowed to establish as many of the quartz crystals are characterized by Dauphine Twin boundaries.