Cristobalitic Stage in the Diagenesis of Diatomaceous Shale

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Science  03 May 1974:
Vol. 184, Issue 4136, pp. 567-568
DOI: 10.1126/science.184.4136.567


With increasing depth of burial, diagenetic cristobalite in the Monterey Shale of California shows a decrease in the d(101) spacing from 4.115 to 4.040 angstroms, indicative of a progressive change in its internal structure. The spacing is 0.004 to 0.015 angstrom smaller in porcellanite than in associated chert, probably because the cristobalite of porcellanite formed later than that of chert.