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U. S. Geological Survey Open-File Report 01-041

A Laboratory Manual for X-Ray Powder Diffraction

LITHIUM SATURATION OF SMECTITES DURING X-RAY POWDER DIFFRACTION

Lithium saturation can be used to distinguish montmorillonite from beidellite. The method described below was modified by Schultz (1969), but is commonly referred to as the Hofmann-Klemen test. If the smectite present in a Li-saturated sample is beidellite, the basal smectite peak will still expand after treatment with ethylene glycol. If the smectite present in a Li-saturated sample is montmorillonite, this peak will stay collapsed after treatment with ethylene glycol. The filter-peel technique described elsewhere in this report may be used when making the oriented-aggregate mounts for lithium saturation. Readers should note that this test does not distinguish between all montmorillonites and beidellites (Wilson, 1987).

PROCEDURE FOR LITHIUM SATURATION 
Materials Required:
  • lithium chloride (LiCl)
  • distilled water
  • graduated cylinder
  • balance
  • weighing paper (4"x4")
  • spatula
  • glass jar with lid
  • glass rod
  • glass petri dishes with covers
  • oven
  • tweezers
  • vacuum pump
  • Millipore filtration device
  • Millipore 47-mm HA 0.45 micron cellulose filters
 Materials required for Lithium saturation procedure.
Weigh out 9.5 g of LiCl for each 100 ml of distilled water used to make the solution. Dissolve the LiCl in the glass jar by stirring with the glass rod to make up a 3N solution of lithium chloride. Weigh out 9.5 g of LiCl for each 100 ml of distilled water used to make the solution.
While making oriented aggregate mounts, pour some LiCl solution into the filtering device and draw the solution with suction through the clays on the filter. Pour some LiCl solution into the filtering device and draw the solution with suction through the clays on the filter.
Remove the moist filter from the filtration device and allow it to dry. Place the dry filter in a petri dish, and let it soak in some of the LiCl solution overnight. Place the dry filter in a petri dish, and let it soak in some of the LiCl solution overnight.
After soaking, carefully remount the filter in the filtering device and run distilled water through the sample and filter to remove any excess LiCl. After soaking, carefully remount the filter in the filtering device and run distilled water through the sample and filter to remove any excess LiCl.
Transfer the clay on the filter to a glass slide as shown in the filter-peel oriented-aggregate mount procedure and keep in an oven overnight at 200 C. Glycolate the samples for at least 4 hours using the vapor-glycolation technique described elsewhere in this report and then analyze the samples by X-ray diffraction. If the 001 smectite peak has expanded, the smectite is beidellite; if the basal peak stays collapsed, the smectite is montmorillonite.

 

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