Ankerite, a dolomite altered by isomorphous cation substitution, is the primary carbonate mineral in Mahogany Zone oil shales of the Green River Formation in Colorado and Utah. X-ray diffraction spacings determined on ten composite samples are shifted from those of unsubstituted dolomite to spacings very similar to an ankerite. Substitution of Fe++ for Mg++ in these samples was insufficient to account for the large shifts detected. Isomorphous substitution of Sr++ for Ca++, suggested as contributing to the shift in spacing, was strongly supported by correlation significant to more than 99 percent between d 104 spacing shift and the proportions of substitution of Fe++ for Mg++ and Sr++ for Ca++ in these samples.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.