• Muscovite has some unique properties.Muscovite molecule image by Vladislav Gajic from Fotolia.com
  
  Muscovite is a naturally occurring mineral that has served a variety of purposes. Although this mineral might not be as sexy as diamonds, its usefulness has helped humankind move from threshold to threshold in evolution. Muscovite is a translucent, slightly colored mineral with a hardness of 2.5 to 3, and a specific gravity of 2.8 to 2.9, yet still proves itself immensely valuable.
  
  

Early Window Glass

• Muscovite's translucence served early humans well.mineral image by Benjamin Herzog from Fotolia.com
  
  Due to the translucent quality of muscovite, earlier humans, in their wish to make a dwelling more comfortable but still see who approaches, realized muscovite made a wonderful window glass. Its ability to resist temperature extremes also served as insulation from the elements, and improved the quality of life for those who could afford it.
  
  

Furnaces and Heaters

• Muscovite resists heat.flame image by Larry from Fotolia.com
  
  In spite of the translucent quality of muscovite, it was also discovered that, when it was cut into sheets, it cleaved well (stayed in a solid sheet), and was resistant to heat. With this attribute, it made sense to use it as a blast window for older styles of furnaces and ovens. Whatever was inside of an oven could often be seen and the heat stayed within. Newer technologies have since replaced muscovite as furnace window glass.
  
  

Circuit Boards

• Mica boards are still around.circuit board image by mite from Fotolia.com
  
  As humans finally broke into the technology era, muscovite once again was used to step up to the next level of ability as a component of circuit boards. Being a silicate, and a monoclinic crystal structure, it made an obvious choice for early computer technicians and designers.
  
  These types of circuit boards are often referred to as "mica boards," and are still available worldwide.