Muscovite is a common rock forming mineral and is found
in igneous, metamorphic and detrital sedimentary rocks.
Muscovite has a layered structure of aluminum silicate
sheets weakly bonded together by layers of potassium
ions. These potassium ion layers produce the perfect
cleavage of muscovite. Although it has such easy cleavage,
the cleavage sheets are quite durable and are often
found in sands that have undergone much erosion and
transport that would have destroyed most other minerals.
The sheets of muscovite also have high heat and electrical
insulating properties and are used to make many electical
components. Muscovite sheets were used for kitchen oven
windows before synthetic materials replaced them.
Muscovite is not often valuable as a mineral specimen
but is often associated with other minerals of extrodinary
beauty and value. Some very nice muscovite crystals
accompany such valuable minerals as tourmaline, topaz,
beryl, almandine and others. A rare twin variety from
Brazil forms yellow five pointed stars and is called
"Star Muscovite". A deep green variety is
called fuchsite and is colored by chromium inpurities.