Geological and mineralogical research were conducted by the scanning probe microscopy and showed that in plagioclase pegmatites of North Baikal muscovite province the average thickness of the peristerites increases from early graphic zones to late trochlear zones and pegmatoid zones of pegmatite veins. The thickness reaches a maximum in the pegmatites of pegmatoid structure which contain large-crystalline muscovite. This regularity can be used for development mineralogical criteria for evaluation of pegmatite veins productivity at the large size muscovite source.
Physico-mathematical modeling has shown that color of iridescent depends on spacing of peristerite lattice. The more spacing lattice, the color of iridescent is higher. The phenomenon of iridescent in plagioclases has an interferential nature. We can select two genetic types of peristerites: peristerites of decomposition and segregation peristerites. Segregation peristerites are formed from postcrystallizational consolidation of peristerites of decomposition. The form of segregation pertisrerites is one of the reasons of polychromatic iridescent genesis in plagioclases.
Spacing of lattice for non-iridescent labradorite, blue-iridescent labradorite, green-iridescent labradorite and red-iridescent labradorite were determined with scanning probe electron microscope. Lattice spacing increases the dynamical trend for different kinds of labradorite, line non-iridescent labradorite (107,5 ± 10 nm), blue-iridescent labradorite (150 ± 10 nm), green-iridescent labradorite (196 ± 10 nm), red-iridescent (231 ± 10 nm). This trend let is state iridescent of these samples to be caused by interference of secondary order.
