## Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

## If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

# Hyperfine Splitting of $Fe^{57}$ and Mg-Fe Order-Disorder in Orthopyroxenes ($MgSiO_{3}-FeSiO_{3}$ Solid Solution)

B. J. Evans, Subrata Ghose and Stefan Hafner
The Journal of Geology
Vol. 75, No. 3 (May, 1967), pp. 306-322
Stable URL: http://www.jstor.org/stable/30071517
Page Count: 17
Preview not available

## Abstract

The apparent "two-line" hyperfine spectrum of $Fe^{57}$ in some orthopyroxene minerals from metamorphic rocks has been analyzed by the Mössbauer technique. The spectrum consists predominantly of two overlapping two-line patterns. The patterns have been assigned to the two non-equivalent $Fe^{2+} sites, M_{1}$ and $M_{2}$, of the crystal structure. The approximated intrinsic values of the electric quadrupole interaction $\frac{1}{2} \mid e^{2}qQ \mid (1 + [\eta^{2}/3])^{1/2}$ and isomer shifts at $M_{1}$ and $M_{2}$ are: The $Fe^{2+}$ site occupancies have been approximately determined. The high degree of Mg-Fe ordering in an orthopyroxene (Fe/[Mg + Fe] = 0.535) found previously by X-ray diffraction has been confirmed. Heat treatment of this sample at 1,000° C. and 1,100° C. yields considerable Mg-Fe disorder.

• 306
• 307
• 308
• 309
• 310
• 311
• 312
• [313]
• 314
• 315
• 316
• 317
• 318
• 319
• 320
• 321
• 322