An Adventure in Glass Archaeology: The Beth She’arim Slab

Dr. Robert Brill excavating beneath the Beth She'arim, slab, Israel, c. 1966.

Dr. Robert Brill excavating beneath the Beth She'arim slab, Israel, c. 1966. Photograph by Paul Perrot. (Rakow item 128612)

In 1956, an enormous slab of a concrete-like substance was discovered by an excavation crew preparing to build a museum in Beth She’arim, Israel.   Seven years later, in 1963, The Corning Museum of Glass and the University of Missouri sent a team of experts to Israel to study ancient glass and discovered the 6.5 x 11 x 1.5-foot slab at Beth She’arim was actually made of glass.  At the time, the slab was the third-largest piece of man-made glass known to exist in the world.  (See The Mystery Slab of Beth She’arim for more information and a video about the slab.)

Almost 50 years after the Museum and the University of Missouri sent their joint team to Israel, the Museum’s Research Scientist Emeritus, Dr. Robert Brill, had some of the slides from his personal archive digitized for the Rakow Research Library’s collection.  These slides of Dr. Brill’s work at Beth She’arim offer a glimpse of the hard work that goes on behind any discovery.

The glass of the Beth She’arim slab weighs almost 9 tons.   When discovered, it lay atop limestone blocks that formed the floor of the tank in which this glass was melted.  As part of the process of researching the slab and its environment, Dr. Brill had to crawl into a space underneath the tank floor – with over 9 tons of material overhead –to obtain a sample of the limestone blocks.  When talking about the picture, Rakow item 128612 (above), Dr. Brill explained that this crawlspace was in an area of the site called “millipede alley,” so named because of all the insects swarming around.   Luckily, he remembered, the millipedes did not bite.

Polished core section of Beth She'arim slab, 7th-9th century, Israel

Polished core section of Beth She'arim slab, 7th-9th century, Israel. Section is approximately 11cm in height. Photograph by Robert Brill, c. 1966. (Rakow Item 127879)

While the scientists working with the Beth She’arim slab may have had to contend with millipedes to collect their samples, these samples were critical in providing much of what we know today about the slab.

The slab was found to be glass with a beautiful raspberry color. Dr. Brill recounted, “The intention had probably been to make glass that could be broken up and shipped elsewhere to be formed into artifacts.”  In other words, the makers of this raspberry glass were not going to be making vessels, jewelry, or other objects themselves.  They were making the raw materials that would be sent to other glassworkers to turn into objects.

Unfortunately, said Dr. Brill, chemical analyses of the raspberry glass showed that it contained too much calcium.  This caused crystals to form during the annealing process, turning the glass opaque.  This is probably why the slab was abandoned, said Dr. Brill.

The crystals that formed due to too much calcium ruined the glass for the ancient workers creating the batch, but another slide from Dr. Brill’s collection, Rakow item 127941, shows that even mistakes can be beautiful:  below is an image of the raspberry glass crystals under a microscope.

Photomicrograph of the crystals in the Beth She'arim slab.

Photomicrograph of crystals formed by devitrification of the glass of the Beth She'arim slab. Photograph by Robert Brill. (Rakow item 127941)

The team of researchers at Beth She’arim performed the hard work of archaeology and running chemical analyses in order to discover the truth about the Beth She’arim slab and why it was abandoned.  To read the fruits of their labor and their final reports, the Rakow Research Library holds copies of two articles, “A Huge Slab of Glass in the Ancient Necropolis of Beth She’arim” and “A Great Glass Slab from Ancient Galilee,” along with many other resources.

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