Answer: muscovite

AnswerCrossword Clue
MUSCOVITECertain Russian
MUSCOVITEBoris Pasternak was one
MUSCOVITERussian
MUSCOVITEMOSCOW: .....
MUSCOVITEMica that's used as an electrical insulator
muscovitea type of mica, used as an insulator
muscoviteA silver-gray form of mica occurring in many igneous and metamorphic rocks