Sapphire, a precious gemstone, is primarily found in igneous rocks and metamorphosed rocks.
Sapphire, which is a variety of the mineral corundum, forms deep within the Earth's crust. According to scientific sources, corundum (including sapphire and ruby) is brought to the surface through specific geological processes.
Igneous Rocks
One key environment where sapphire is found is within igneous rocks. Specifically, these are igneous rocks that meet certain chemical criteria:
- High in aluminium: The formation of corundum requires a high concentration of aluminium.
- Low in silicon: A low silicon content is crucial, as high silicon would favor the formation of other minerals like feldspar instead of corundum.
Examples of igneous rocks that fit this description and can host sapphire deposits include basalts. As magma from deep within the Earth rises and cools, it can carry these newly formed corundum crystals to the surface.
Metamorphosed Rocks
Sapphire is also found in rocks that have undergone metamorphosis. Metamorphic rocks are formed when existing rocks (igneous, sedimentary, or other metamorphic rocks) are subjected to intense heat, pressure, or chemical reactions deep within the Earth's crust. These conditions can cause minerals within the rock to recrystallize or new minerals like corundum to form, leading to sapphire deposits in various metamorphic rock types such as marble or schist.
In summary, based on geological evidence, sapphire is found in:
- Igneous rocks: Particularly those rich in aluminium and low in silicon, such as basalts.
- Metamorphosed rocks: Rocks that have been transformed by heat and pressure.
Understanding the geological context of sapphire formation helps geologists locate potential deposits and provides insight into the incredible forces that create these beautiful gemstones.
