Mica Polytypes: Systematic Description and Identification

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Science  14 Jan 1966:
Vol. 151, Issue 3707, pp. 191-193
DOI: 10.1126/science.151.3707.191


X-ray studies of mica specimens from a variety of geological localities show that biotite and certain lithium-rich mica samples are composed of a mixture of different polytypes. Many of the biotite structures are new complex polytypes not before reported. A new method of designating mica polytypes is proposed. Techniques are described for the systematic generation of all the possible layer-stacking sequences of mica polytypes and for the verification of the stacking sequences in newly discovered forms.