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No. 119: Sep-Oct 1998

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Basalt Synthesis Invented Over 3,000 Years Ago!

Basalt is a blackish volcanic rock that is hard and durable. In nature it sometimes occurs in long prisms of hexagonal cross section. In fact, ancient Micronesians quarried multiton basalt prisms to build their fantastic megalithic complex of 92 artificial islets at Nan Madol. (SF#45)

The inhabitants of ancient Mesopotamia had no basalt quarries at hand. Indeed, building stone of any kind was exceedingly scarce. What the Mesopotamians of the second century B.C. did have in abundance was alluvial silt. From this unpromising material they were able to make their pottery, writing tablets, and art objects. However, for grinding grain and engineering structures they needed something harder and stronger. Their innovative solution was: artificial basalt made from silt. They simply melted the silt and let it cool slowly.

Sounds simple, but three remarkable intellectual and technical advances were required:

  1. The Mesopotamians first had to recognize that silt could be melted. This could not have been obvious in 1000 BC.
  2. Next, they had to develop hightemperature (1,200C) smelters that were much larger than those they used for metallurgical purposes.
  3. Finally, they had to discover that slow cooling was needed for the growth of large crystals in the cooling melt. (Of course, they had no microscopes to see the crystals. So, it had to have been something learned from experience.)

That the Mesopotamians were able to synthesize basalt can be seen at Mashkanshapir about 80 kilometers south of Baghdad. Slabs of this artificial rock -- flat and smooth on one side from the molds -- are abundant. In fact, some 100 cubic meters of the material have been found.

(Stone, E.C., et al; "From Shifting Silt to Solid Stone: The Manufacture of Synthetic Basalt in Ancient Mesopotamia," Science, 280:2091, 1998. Also: Bower, B.; "Ancient Mesopotamians Made Rock from Silt," Science News, 153:407, 1998.)

Comments. In the light of the Mesopotamian's success in making artificial stone, perhaps we should reconsider Davidovits' claim that the ancient Egyptians cast some of the blocks they used to build the pyramids. In other words, they, too, made artificial stone at the sites of the pyramids. (SF#34 and SF#54)

We can't resist remarking that the first-author's name jibes with the subject at hand. A variety of "nominative determinism"?

From Science Frontiers #119, SEP-OCT 1998. 1998-2000 William R. Corliss