Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Chinese used diamonds to polish sapphire-rich stone in 2500 BC


Find provides evidence of earliest known use of diamond and sapphire by prehistoric people

Researchers have uncovered strong evidence that the ancient Chinese used diamonds to grind and polish ceremonial stone burial axes as long as 6,000 years ago -– and incredibly, did so with a level of skill difficult to achieve even with modern polishing techniques. The finding, reported in the February issue of the journal Archaeometry, places this earliest known use of diamond worldwide thousands of years earlier than the gem is known to have been used elsewhere.

The work also represents the only known prehistoric use of sapphire: The stone worked into polished axes by China’s Liangzhu and Sanxingcun cultures around 4000 to 2500 BC has as its most abundant element the mineral corundum, known as ruby in its red form and sapphire in all other colors. Most other known prehistoric artifacts were fashioned from rocks and minerals no harder than quartz. "The physics of polishing is poorly understood; it’s really more an art than a science," says author Peter J. Lu, a graduate student in physics at Harvard University’s Graduate School of Arts and Sciences. "Still, it’s absolutely remarkable that with the best polishing technologies available today, we couldn’t achieve a surface as flat and smooth as was produced 5,000 years ago."

Lu’s work may eventually yield new insights into the origins of ancient China’s trademark Neolithic artifacts, vast quantities of finely polished jade objects. Lu began the research in 1999, as a Princeton University undergraduate. He studied four ceremonial axes, ranging in size from 13 to 22 centimeters, found at the tombs of wealthy individuals. Three of these axes, dating to the Sanxingcun culture of 4000 to 3800 BC and the later Liangzhu culture, came from the Nanjing Museum in China; the fourth, discovered at a Liangzhu culture site at Zhejiang Yuhang Wujiabu in 1993, dates roughly to 2500 BC. "What’s most amazing about these mottled brown and grey stones is that they have been polished to a mirror-like luster," Lu says. "It had been assumed that quartz was used to grind the stones, but it struck me as unlikely that such a fine finish could be the product of polishing with quartz sand."

Lu’s subsequent X-ray diffraction, electron microprobe analysis, and scanning electron microscopy of the four axes’ composition gave more evidence that quartz could not have polished the stones: Fully 40 percent corundum, the second-hardest material on earth, the only material that could plausibly have been used to finish them so finely was diamond.

To further test whether diamond might have been used to polish the axes, Lu subjected samples of the fourth axe, 4,500 years old and from the Liangzhu culture, to modern machine polishing with diamond, alumina, and a quartz-based silica abrasive. Using an atomic force microscope to examine the polished surfaces on a nanometer scale, he determined that the axe’s original, exceptionally smooth surface most closely resembled -– although was still superior to -– modern polishing with diamond.

The use of diamond by Liangzhu craftsmen is geologically plausible, as diamond sources exist within 150 miles of where the burial axes studied by Lu were found. These ancient workers might have sorted diamonds from gravel using an age-old technique where wet diamond-bearing gravels are run over a greased surface such as a fatty animal hide; only the diamonds adhere to the grease.

The next known use of diamond occurred around 500 BC; it was used after 250 BC in ancient India to drill beads. The earliest authors to reference what is likely diamond, Manilius and Pliny the Elder, lived in Rome during the first century AD.

Lu’s co-authors are Paul M. Chaikin of New York University; Nan Yao of Princeton University; Jenny F. So of the Chinese University of Hong Kong; George E. Harlow of the American Museum of Natural History; and Lu Jianfang and Wang Genfu of the Nanjing Museum. The work was supported primarily by Harvard University’s Asia Center, with additional support from MRSEC grants and Princeton University’s Department of Physics.

Steve Bradt | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Identifying New Sources of Turbulence in Spherical Tokamaks
30.11.2015 | Princeton Plasma Physics Laboratory

nachricht Graphene microphone outperforms traditional nickel and offers ultrasonic reach
27.11.2015 | Institute of Physics

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How Cells in the Developing Ear ‘Practice’ Hearing

Before the fluid of the middle ear drains and sound waves penetrate for the first time, the inner ear cells of newborn rodents practice for their big debut. Researchers at Johns Hopkins report they have figured out the molecular chain of events that enables the cells to make “sounds” on their own, essentially “practicing” their ability to process sounds in the world around them.

The researchers, who describe their experiments in the Dec. 3 edition of the journal Cell, show how hair cells in the inner ear can be activated in the absence...

Im Focus: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

All Focus news of the innovation-report >>>



Event News

Urbanisation and migration from rural areas challenging agriculture in Eastern Europe

30.11.2015 | Event News

Fraunhofer’s Urban Futures Conference: 2 days in the city of the future

25.11.2015 | Event News

Gluten oder nicht Gluten? Überempfindlichkeit auf Weizen kann unterschiedliche Ursachen haben

17.11.2015 | Event News

Latest News

Teamplay IT solution enables more efficient use of protocols

30.11.2015 | Trade Fair News

Greater efficiency and potentially reduced costs with new MRI applications

30.11.2015 | Trade Fair News

Modular syngo.plaza as a comprehensive solution – even for enterprise radiology

30.11.2015 | Trade Fair News

More VideoLinks >>>