Clays and Clay Minerals

, Volume 14, Issue 1, pp 91–98 | Cite as

Concentration of Dioctahedeal Mica and Vermiculite using a Fluoride Solution

  • C. I. Rich
Symposium on Structure and Quantitative Analysis


A Solution containing fluoride (0.4 n NH4F, 0.1 n HCl, n NH4Cl), permits the concentration of dioctahedral mica and dioctahedral vermiculite in mixed clay systems. Allophane, halloysite, kaolinite, and in particular, Mg-rich montmorillonite, biotite, and vermiculite of clay size, are destroyed in 24–48 hr at room temperature. A salt-free, NH4-saturated sample, weighing 80 mg, is shaken in 80 ml of the fluoride solution. The residue is washed with water and X-ray diffraction patterns made.

The method has use in characterizing some of the 2:1 layer silicates in clays. Anatase, if present, is also concentrated and is more positively identified by X-ray diffraction.


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Copyright information

© Clay Minerals Society 1966

Authors and Affiliations

  • C. I. Rich
    • 1
  1. 1.Department of AgronomyVirginia Polytechnic InstituteBlacksburgUSA

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