Sapphires, highly valuable gems made of chemically “contaminated” aluminum oxide, are typically found in association with silicon-poor volcanic rocks, leading many to believe they originate in deep crustal rocks and are brought to the Earth’s surface through volcanic activity. A study conducted by geoscientists at Heidelberg University focused on sapphires found in the Eifel region of Germany, known for its volcanic activity. The research aimed to understand why sapphires are commonly found in volcanic deposits rich in sodium and potassium. The researchers, led by Prof. Dr. Axel Schmitt, examined 223 sapphires from the Eifel, with most of them recovered from river sediments due to their resistance to weathering.
The age of the sapphires from the Eifel was determined using the uranium-lead method on mineral inclusions in the sapphires, as well as analyzing oxygen isotopes to identify the crystals’ origin. The researchers found that the sapphires formed at the same time as the volcanic activity in the region, inheriting isotopic signatures from both mantle melts and crustal rocks. They discovered that sapphires in the Eifel formed through a combination of magmatic and metamorphic processes, with some originating from contact with subterranean melts that triggered sapphire formation. These findings challenge the traditional belief that sapphires are simply brought to the surface by magma.
The study sheds light on the formation of sapphires in volcanic regions and provides insights into the processes that lead to the creation of these valuable gemstones. The research was published in the journal “Contributions to Mineralogy and Petrology” and received support from the Dr. Eduard Gübelin Association for Research and Identification of Precious Stones in Switzerland and the German Research Foundation. By conducting geochemical analyses on sapphires from the Eifel region, the researchers were able to unravel the complex processes involved in the formation of these precious gems, contributing to our understanding of their geological origins.
The presence of sapphires in volcanic deposits in the Eifel region of Germany has long been a mystery, with their association with sodium and potassium-rich magmas raising questions about their origin. The study conducted by geoscientists at Heidelberg University provided new insights into the formation of sapphires in volcanic regions by analyzing sapphires from the Eifel using advanced dating techniques and isotopic analysis. The research revealed that sapphires in the Eifel formed through a combination of magmatic and metamorphic processes, challenging conventional theories about the origin of these gemstones.
The discovery that sapphires in the Eifel formed concurrently with volcanic activity and inherited isotopic signatures from both mantle melts and crustal rocks provides a more nuanced understanding of the geological processes involved in sapphire formation. The research not only enhances our knowledge of sapphire formation but also underscores the importance of conducting detailed geochemical analyses to unravel the complexities of gemstone origins. The findings of the study have significant implications for the field of gemology and mineralogy, offering a new perspective on the formation of sapphires in volcanic regions like the Eifel.
