Emily Chan
Like many precious gemstones, sapphires originate in the bowels of the Earth’s crust. However, the exact process that led to the formation of these sparkling blue crystals has eluded scientists until now.
In a recent study, researchers from Heidelburg University have been studying the formation of sapphires in volcanic regions, giving rise to new insights into the origins of sapphires.
The main ingredient in sapphires is a form of aluminum oxide. There are also traces of iron, titanium, lead, cobalt, chromium, magnesium, boron, silicon, and vanadium. Their brilliant blue hue comes from these trace elements, particularly titanium and iron.
They interact with the crystal lattice and absorb wavelengths of light in the red and yellow parts of the spectrum.
When those wavelengths are absorbed, the remaining reflected light is mostly blue, resulting in a rich azure color.
The cocktail of elements is derived naturally from ancient volcanic rock that is low in silicon dioxide but full of sodium and potassium.
The researchers studied 223 sapphires found in the Eifel mountain range of western Germany. The Eifel is a volcanic region where magma from the Earth’s mantle has been penetrating the crust for almost 700,000 years.
Experts didn’t know why sapphires are frequently found in these areas, but the researchers discovered that volcanic activity was the answer.
They believed that sapphires in the Earth’s crust originated from clay sediments at high temperatures. As magma ascended and pressure was built up, the crystals ended up on the Earth’s surface.
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