300
Muscovite is a shiny mineral that can be pulled apart into thin sheets. For many years, it was used like a material we can easily get today.
Name two ways people used this mineral.
* People used it to make windows.
*Thin transparent sheets of mica called "isinglass" were used for peepholes in potbelly stoves and lanterns because they were less likely to shatter compared to glass when exposed to extreme temperature gradients.