Gemstones Formed by Low-Pressure Regional Metamorphism: The Ruby Deposits of Mogok, Burma

  • Peter C. Keller


Low-pressure metamorphism can take place locally, as contact metamorphism, or over large areas, as regional metamorphism (Figure 6–1). When hot magma intrudes into the cool surrounding rock, the rock is heated and saturated by hydrothermal fluids and commonly undergoes change in the form of replacement of some of its component minerals or recrystallization of the entire rock mass. The type and degree of change are dependent upon the temperature and chemistry of the intruding magma and the type of rock subjected to the intrusion. Resistant, unreactive rocks, such as quartzites and sandstones, may go unchanged when invaded by the molten rock. Others, most dramatically carbonates such as limestones, may undergo tremendous change due to their chemical reactivity. If the carbonate rock is magnesium rich, such as dolomite, magnesium minerals such as diopside or serpentine form. Likewise, the invading rock also contributes elements, the most common of which is silica.


Granitic Rock Regional Metamorphism Contact Metamorphism Biotite Schist Voluntary Liquidation 
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Copyright information

© Van Nostrand Reinhold 1990

Authors and Affiliations

  • Peter C. Keller
    • 1
  1. 1.Natural History Museum of Los Angeles CountyUSA

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