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Constancy of the Sum of Mica Unit Cell Potassium Surface and Interlayer Sorption Surface in Vermiculite‐Illite Clays
Author(s) -
Mehra O. P.,
Jackson M. L.
Publication year - 1959
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1959.03615995002300020007x
Subject(s) - mica , sorption , vermiculite , illite , chemistry , planar , kaolinite , cleavage (geology) , muscovite , montmorillonite , potassium , mineralogy , analytical chemistry (journal) , gravimetric analysis , clay minerals , materials science , adsorption , chromatography , quartz , organic chemistry , composite material , computer graphics (images) , fracture (geology) , computer science
The total unit cell planar specific surface was computed as the sum of planar sorption surface (by a glycerol gravimetric method) and the mica unit cell interplanar surface (corresponding to the K). This sum was found to be constant for a given unit cell formula weight, averaging 773 m. 2 /g. with a standard deviation of ±12.7 or about ±2%. For example, a Colorado vermiculite had 1.63% K 2 O equivalent to 16.3% mica residue with a unit cell interplanar surface of 124 m. 2 /g.; this added to the measured 631 m. 2 /g. of planar sorption surface (glycerol sorbed on expanded or cleavage planes) gives a total planar surface of 755 m. 2 /g. Similarly, for coarse clay from Fithian, Illinois, the 5.61% K 2 O is equivalent to 56.1% of illite, with unit cell interplanar surface of 426 m. 2 /g. This, added to 235 m. 2 /g. of measured planar sorption surface, gives a total of 661 m. 2 /g. which when corrected to exclude 15% unexpanded minerals (kaolinite and chlorite) gives a total planar specific surface of 775 m. 2 /g. Wyoming montmorillonite had 803 m. 2 /g. of planar specific surface, comparing well with the theoretical, 808 m. 2 /g. This principle of unit cell planar specific surface constancy of 2:1 layer silicates shows that the mechanism of K release from mica is by cleavage, and gives an accurate tool for analysis of the rather generally occurring interstratified mixtures of expanding 2:1 layer silicate minerals with micas in soils and sediments.