A rapid method for hand picking potassium-rich feldspar from silicic tephra

作者：Hynek Scott A^*; Brown Francis H; Fernandez Diego P

来源：Quaternary Geochronology, 2011, 6(2): 285-288.

DOI：10.1016/j.quageo.2010.11.004

• Mineral separation
• Staining
• Feldspar
• Sodium cobaltinitrite
• Sanidine
• Cerro Galan

We detail a method for hand picking potassium-rich feldspars from silicic tephra. The method, based on the well known sodium cobaltinitrite staining technique, is applicable to any sample where K content of feldspar exceeds similar to 2 wt%. The method is well suited to mineral grains > 0.25 mm and useful for grains as small as similar to 0.125 mm. Alkali feldspar, plagioclase, and quartz are easily distinguishable after staining. Rinsing the stained feldspars along with ultrasonic treatment in distilled water and nitric acid removes the stain. (40)Ar/(39)Ar analysis of sanidine separated by staining yields precise age estimates which are in excellent agreement with published ages for the youngest (2.06 Ma) Cerro Galan ignimbrite, NW Argentina.

• 出版日期2011-4