Silicon diffusion was measured in natural quartz under dry low-pressure (0.1MPa) conditions using a 30Si tracer. The sources of diffusant consisted of 30Si-enriched silica powder. Distributions of 30Si were measured using Rutherford back-scattering spectrometry and nuclear reaction analysis using the reaction, 30Si(p,γ)31P. The Arrhenius relationships for anneals at 1atm in air were:

Normal to c:     D(m2/s) = 7.97 x 10-6 exp[-447(kJ/mol)/RT]

Parallel to c:     D(m2/s) = 6.40 x 10-6 exp[-443(kJ/mol)/RT]

D.J.Cherniak: Earth and Planetary Science Letters, 2003, 214[3-4], 655-68