The presence of intrusive magma in an area (known as contact
metamorphism), or of tectonic plate interactions on a larger scale
(known as regional metamorphism) puts the igneous and sedimentary
rocks and minerals under heat or pressure which may cause changes
in their chemistry and crystal structure. The result is the
creation of metamorphic rocks. Gemstones associated with
metamorphic rock include the beryls, jade, lapis lazuli, turquoise,
spinel, ruby, sapphire and zircon.