Cobalt-Blue Glass Cup from 'Heavenly Horse Tomb’

"천마총 유리잔 성분, 동지중해·흑해 제작說 뒷받침"

송고시간 | 2019-11-24 06:30

국립경주박물관, 분석 결과 발표…"이집트서 주로 나오는 재료 있어"

「天馬塚グラス成分、東地中海・黒海製作說裏付け"

国立慶州博物館、分析結果を発表... 「エジプトでは主に出てくる材料おり "

Seoul, Nov. 24 (Yonhap) -- As a result of the analysis of the Blue glass cup from Cheonmachong Tomb, the 'Heavenly Horse Tomb’ in Gyeongju, the former capital city of the millenium kingdom Silla, it have been submitted from the cultural heritage conservation science world that the existing academic opinion that it was made on the East Middle Sea or the Black Sea coast is likely to be true. 

Researchers from the National Museum of Gyeongju will unveil their findings at the 2019 International Symposium "Ancient Glass in the World from East Mediterranean Sea to East Asia" hosted by the museum. 

At the symposium, Korean, Japanese and British researchers present seven themes about ancient glass. 

They said on the 24th that they made the conclusion by examining the Blue glass cup, designated as Treasure No. 620 of Korea, in terms of conservation science. 

The glass cup excavated in 1973 frrom the tomb, which is believed to have been built in the late 5th or early 6th century, are 7.4cm high and 7.8cm in diameter at the top. Originally two items were found, but the other one was so damaged that it could not be restored. 

The cup is cobalt-blue in color and features very few bubbles in the glass. 

On the basis of the similar glass ware found on Europe and the Black Sea coast, scholars have claimed that the cup was made there and importe into the Korean peninsula. 

The Korean researchers along with the  Okayama Museum of Oriental Art in Japan conducted a scientific analysis using the non-destructive test for the cup. 

As a result, "The amount of potassium oxide is 0.66wt% (mass percent), and the magnesium oxide is 0.93wt% or less, all 1.5wt% or less." "This clearly shows that it is Natron-based soda-lime glass." said they. 

"Natron-based glass ware was distributed around Rome from 800 B.C.E. to 800 B.C., and When glass ware was made, it was mixed in Egypt with natural sodium carbonate, called Natron, instead of general Flux plants." "thus, the potassium oxide and magnesium oxide contents are remarkably low." they added. 

"This mineral was the main material for making glass ware in ancient Rome because it was mined mainly in Egypt, and it is difficult to find such a chemical composition in ancient glass in other regions." "The glass cup was probably first processed in the Middle East or Black Sea coast," said the reaearchers. 

"While glass products can be processed first and second in different time and space, most of them are second-processed in the first processing place, except in special cases."

Primary processing is the process of mixing minerals or plant ashes with silicon dioxide and heating them to form liquefied glass, secondary processing is the process of making a specific form of objects such as a cup or bowl. 

In other to find out techniques for making the turtle-shaped bottom of the cup, the researchers performed CT scans with equipment at the National Museum of Korea to confirm that the hexagonal (or pentagonal) surface part was concave, whereas the edges were thickened. 

"These shapes do not explain the production process sufficiently by placing them on a frame with holes and blowing them." "Considering the inner curvature of the cup, we have to assume a different hypothesis about the fabrication technique," they insisted.

"The glass cup is generally thick, with a thickness of 1.3-3.6mm," they dded. "The glass vessel was made by a professional craftsman to show the luxury and practicality."