sentences:  In 1956, a bulldozer working at the site unearthed an enormous rectangular slab, 11 × 6.5 × 1.5 feet, weighing 9 tons.Initially, it was paved over, but it was eventually studied and found to be a gigantic piece of glass.A glassmaking furnace was located here in the 9th century during the Abbasid period, which produced great batches of molten glass that were cooled and later broken into small pieces for crafting glass vessels.