Clay Mineralogy Exercise - Calculating mixed-layer patterns

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 2-theta, using 0.02 increments.

  1. chlorite/smectite R=0, fractions: 0.0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0
  2. chlorite/smectite R=1, fractions: 0.5, 0.6, 0.7, 0.8, 0.9, 1.0
  3. Biotite with Mg:Fe ratios  1:0 , 0.75:0.25 , 0.5:0.5 , 0.25:0.75 , 0:1

Hint: To simulate biotite, use a trioctahedral mica layer type, and vary the  Fe per Si4O10.

Make an overlay plot of each set.


Part B.

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