CHEMICAL ISOLATION OF QUARTZ FOR MEASUREMENT OF INSITU-PRODUCED COSMOGENIC NUCLIDES

An isolation method relying totally on chemical steps was developed to separate large quantities (10-200 g) of clean mono-minerallic quartz samples from a variety of terrestrial rocks and soils for the purpose of measuring Be-10(t1/2 = 1.5 Myr) and Al-26(t1/2 = 0.705 Myr) produced by cosmic rays in situ in the quartz phase. The procedure consists of grinding the sample, heating it in HCl, and treating it with a series of leaches using a dilute HF/HNO3 mixture in a heated ultrasonic tank. The purified quartz was also used for the measurements of in-situ-cosmic-ray-produced Ne-21 and C-14(t1/2 = 5730 yr). The method is applicable to any problem requiring purified quartz on a large scale.