Habit: micaceous, scaly, lamellar.
Color: brown, gray, green, yellow, or reddish brown.
Streak: white.
Diaphaneity: transparent to translucent.
Luster: vitreous, pearly.
Cleavage: (001) perfect.
Fracture: uneven.
Twinning: [310].
Dielectric properties.
Relative
permittivity: 6.5 to 8.7, dielectric field strength: 50–150 kV/mm, loss tangent 0.004 to 0.070,
electrical resistivity 1012 to 1015 ohm.m.
Occurrence: contact and regional metamorphic
limestones and dolomites.
Phlogopite is one of the most commonly present micas
and is denoted as K(Mg,Fe)3AlSi3O10(OH,F)2.Mica is
commonly found as small flakes or lamellar plates
without a crystal outline. Thin cleavage sheets of mica,
particularly muscovite and phlogopite, are elastic,
flexible and tough. They range from translucent to
transparent. They have low electrical and thermal
conductivity and high dielectric strength, and hence are
used as electrical insulators.
