November 26, 1922 archaeologist Howard Carter (1874-1939) entered the tomb of Tutankhamun, pharaoh in ancient Egypt from 1332 to 1323 BC. The grave was filled with precious jewelry, including a breastplate decorated with a scarab, made from a greenish-yellow gemstone.
Fig.1. Pendant found in Tutankhamun's tomb with gemstone of desert glass, photo by Jon Bodsworth (Wikipedia-Commons, image in public domain).
At first the gem was identified as chalcedony, a variety of quartz. However in December 1932 the British geologist Patrick Clayton, exploring the Libyan desert, discovered some strange pieces of green glass emerging from the sand. He published his discovery together with mineralogist Leonard Spencer (1870-1959) from the British Museum, suggesting that the strange material formed as a layer of silica deposits on the bottom of a (now dry) lake.
However modern researchers discovered minerals like lechatelierite and baddeleyite inside the glass, quartz- and zircon-varieties that form only under high temperature or pressure, also traces of iron, nickel, chromium, cobalt and iridium - trace elements rare in earth's rocks, but frequent in meteorites.
Today the desert glass is explained as tektites - the ubiquitous sand was suddenly molten by the impact of a meteorite, quickly cooling in the air, droplets of glass rained down on the Libyan desert, where the greenish gemstone was collected already 3000 years ago.
Precious stones and metals played an important in Ancient Egypt. Already in 3200 BC professional geological prospectors, called "sementi", searched for deposits and veins, mostly of gold. This yellow metal was associated with the sun and the divine pharaoh and played an important role in the religion of the Egyptians, so it's no wonder that Tutankhamun's tomb was filled with more than 500 items, many made of pure gold.
In Pharaonic times gold was found in southern Egypt , but most was imported from the ancient kingdom of Nubia (modern Sudan). Greek historian Herodotus reports that in the Nubian capital of Meroä gold was more common and less valued than copper! Following the ancient descriptions British geologists discovered in 1901-1903 more than 85 ancient mines in the region, however the ancient miners had worked well - no ore remained to be found.
However Howard Carter, confronted with all the treasures, with all the gold and gems, remembers what he considered as the most precious gift given to the deceased king - the dried remains of flowers, presumably left by Tutankhamun's wife there, were still to be found inside the sarcophagus.
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