Pegmatites

Описание: This video is about pegmatites. Pegmatites are any rock that has larger than normal mineral crystals.
 Most pegmatites form in granite and have larger than normal crystals of quartz feldspar biotite mica and muscovite mica.
Granite pegmatites occur in Granite bodies all along the eastern United States and most were in place during the Alleghanian orogeny or mountain building event.
The presence of abundant water in the granite magma enables large mineral crystals to form.
An element like water that enables large mineral crystals form is called a volatile element. Lithium and sulfur or also volatile elements that perform this function.
There are several locations along the eastern United States where granite pegmatites occurred with very large pieces of muscovite mica in them. Most of these have given rise to mica mines. Most of these mica mines are no longer functional but one in Heartwell Georgia is currently operating. Today mica is used primarily in face make up lipgloss and the shiny affect given to automotive body paint.
On rare occasions granite magma bodies contain not only volatile elements like water but also exotic elements like beryllium, tourmaline, garnet ( a mineral), dumortierite and boron. These exotic elements give rise to beautiful precious and semi precious gemstones like beryl, aquamarine, emerald, hiddenite, tourmaline, garnet and rose quartz.