Clay Mineralogy Exercise #5

Part A.

Using NEWMOD, calculate the diffraction patterns and determine the peak positions for the mixed-layer clay reflections listed below. Do this for each of the fractions indicated below. Calculate your pattern using Co K-alpha radiation over the range of 2-45° 2Q, using 0.02° increments.

  1. Illite/smectite R=0, fractions: 0, 0.1, 0.2, 0.3, 0.4, 0.5
  2. Illite/smectite R=1, fractions: 0.5, 0.6, 0.7, 0.8, 0.9, 1.0
  3. Biotite/vermiculite,  R=1, fractions: 0.3, 0.4, 0.5, 0.6, 0.7
  4. Biotite/vermiculite, R=3, fractions: 0.7, 0.8, 0.9, 1.0

Hint: To simulate biotite, use a trioctahedral mica layer type, with 1 Fe per Si4O10.

For sets above mark the peak positions and determine the FWHM using the NEWMOD peak finding feature. Make plots of each.

Part B.

Calculate the line broadening Q values for the 0.9 fraction illite/smectite, R = 1. Do this for l = 1, 2, 3, 4, 5, 6, 7, 8.