Mica - Explanation and use
It is believed that the name mica has been derived from the Latin word micare,
which means to shine or glitter. The term describes a group of complex hydrous aluminium
silicate minerals. Crystals of mica exhibit perfect basal cleavage and split easily into
tough, flexible platelets or sheets. The thinnest platelet producible is determined essentially
by mechanical considerations.
There is considerable variation in the chemical composition of the mica minerals. These minerals
are distinguished by the presence of metallic cations, principally potassium, iron, magnesium and
aluminium. The commercially most important types of mica are Muscovite mica, a potassium
aluminium silicate, Phlogopite mica, a magnesium-iron aluminium silicate and Biotite mica
which is the high iron member of this series.
Mica deposits are found throughout the world in Europe, the North and South Americas, in Africa, India and
China. We in Mahlwerk Neubauer-Friedrich Geffers GmbH are processing and dealing solely natural
muscovite mica in dry, wet ground and calcined form.
Dry grinding mica to flakes or powder form has a tendency to pulverize the mica producing particles
that are more granular in shape rather than thin platelets. Wet grinding is done in a water based
environment and applies enormous shearing forces on the mica delaminating the sheets into thin
platelets. However, the economics of wet grinding versus dry grinding often dictate the use of the
lower cost dry ground materials presuming the benefits provided are sufficient for the application.
In building materials, paints, plastics, welding electrodes, foundry works, cosmetics and other
end-uses including oil drilling ground mica is typically used as filler. In rubber applications mica
is used as a mold release agent in the priming of rubber products.