It weighs 9 tons.
Although chemical analysis confirm its glass, the slab doesnt look anything like the delicate, translucent material.
Rather, it looks like a large block of limestone, for it is completely opaque and bluish-gray.
An attempt was made to dislodge the slab, but the slab was too heavy for the bulldozer.
The Great Glass Slab at Beth Shearim.
A piece of the slab was broken off and sent to the labs for testing.
The results stunned everyone, including the researchers themselves.
The slab was indeed made of glass, and it was 1,600 years old.
Humans have been making glass for 6,000 years, much longer than they have been making iron tools.
These early glasses were rarely transparent and often contained impurities and imperfections.
The glass slab at Beth Shearim is an example of such a failure.
Why did the glass slab at Beit She’arim fail?
Polished core section of Beth She’arim slab, 7th-9th century, Israel.
Section is approximately 11cm in height.
The tank was filled with around 11 tons of raw material and heated to 1100C.
This must have required as much as 20 tons of fuel.
At the very bottom was some of the original batch, which looks coffee grounds.
Apparently, the heat had not penetrated all the way through, so the slab was essentially half baked.
The result was a solid block of solidified silica.
Consequently, the glass was never broken up to be used for making vessels.
Had the glass turned out perfect, it could have produced 50 to 60 thousand small vessels.
Photomicrograph of crystals formed by devitrification of the glass of the Beth She’arim slab.
