Mineral Species: Muscovite

Chemical Formula: KAl2(AlSi3O10)(F,OH)2

Chemical Name: Potassium Aluminium Silicate Hydroxide Fluoride

Mineral Class: Phyllosilicate

Mineral Notes: Muscovite is a common rock forming mineral and is found in igneous, metamorphic and detrital sedimentary rocks. It has a layered structure of aluminum silicate sheets weakly bonded by layers of potassium. These potassium ion layers produce the perfect cleavage of muscovite. Although it has such easy cleavage, the sheets are durable. They have high heat and electrical insulating properties and are used to make electical components. Muscovite sheets were used for oven windows before synthetic materials replaced them. 

Description: An excellent example of Muscovite commonly known as "Star" Muscovite, for its star-shaped crystals. The habit forms due to twinning. In addition, the colour and waxy luster, make this a very attractive display specimen.

Location: Araçuaí, Minas Gerais, Southeast Region, Brazil.