thumbnail

Crystal structure refinement and Mössbauer spectroscopy of an ordered, triclinic clinochlore

Clays and Clay Minerals

By:
, , , , and
DOI: 10.1346/CCMN.1997.0450406

Links

Abstract

The crystal structure of a natural, ordered IIb-4 triclinic clinochlore has been refined in space group C1¯ from 4282 unique X-ray intensity measurements of which 3833 are greater than 3 times the statistical counting error (3σ). Unit cell parameters are a = 5.3262(6) Å; b = 9.226(1) Å; c = 14.334(3) Å; α = 90.56(2)°; β = 97.47(2)°; and γ = 89.979(9)°, which represents the greatest deviation from monoclinic symmetry yet recorded for a triclinic chlorite. The final weighted R is 0.059 for reflections with I > 3σ and 0.064 for all reflections. The chemical formula is (Mg0.966Fe0.034)M1(Mg0.962Fe0.038)M22(Si2.96Al1.04)O10 (OH)2(Mg0.996Fe0.004)M32(Al0.841FeIII0.102Cr0.004Ti0.004)M4(OH)6, which is consistent with electron microprobe (EMP), wet chemical analyses, Mössbauer spectroscopy and X-ray structure refinement. The high degree of ordering of the divalent versus trivalent octahedral cations in the interlayer is noteworthy, with FeIII and Al in M4 and virtually no Fe in M3. In the 2:1 layer, M1 and M2 each contain similar amounts of Fe. The 2 tetrahedral sites have nearly identical mean oxygen distances and volumes, and thus show no evidence of long-range cation ordering.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Crystal structure refinement and Mössbauer spectroscopy of an ordered, triclinic clinochlore
Series title:
Clays and Clay Minerals
DOI:
10.1346/CCMN.1997.0450406
Volume
45
Issue:
4
Year Published:
1997
Language:
English
Publisher:
The Clay Minerals Society
Description:
7 p.
First page:
544
Last page:
550
Online Only (Y/N):
N
Additional Online Files(Y/N):
N