fig11

Figure 11. (A) Classification of quartz by raw material price and mineral type^[59]; (B) XRF analysis of potassium feldspar in quartz^[62]; (C) Electron probe microscopy of potassium feldspar; (D) EPR determination of elemental lattice impurities in quartz; (E) Raman spectroscopy of white mica inclusions in quartz Purification of quartz; (F) Upper limit of IOTA standard quartz and high-purity quartz element^[27]. EPR: Electron paramagnetic resonance; IOTA: International Oligomer Trading Association; XRF: X-ray fluorescence.