1. Crystal lattice of muscovite
Mica is a group of minerals, which
belongs to the sheet minerals (phyllosilicates). They form thin, flexible
platelets. For refractory purposes the bright mica (muscovite) is used,
which is characterised by its high content of potassium (cf.
chemical data). Mica indicates a relatively low melting point, so that
it can not be used alone, but only in combination with other refractory
fillers such as talc or pyrophyllite.