H. Takeda D. R. Wones M. Ross 1966 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. application/pdf 10.1126/science.151.3707.191 en American Association for the Advancement of Science Mica polytypes: Systematic description and identification article