I dug out the book and looked it up
I remembered other large blocks being noted but they were the three noted in the article upon which the temple of Jupiter at Baalbeck is constructed.
Haliburton indicates the weight as 1,200 tons and the size being 68’ x 14’ x14’ or 13328 cubic feet at 150 pcf = 999.9 tons. so I guess he used a density of 180 pcf
There are three at Baalbek, they have been known throughout historical times, so there’s no surprise that Halliburton knew about those. As the article states, another stone that had been left at or near the quarry site and never made it to the temple site, “dubbed Hajjar al-Hibla, or ‘stone of the pregnant woman’” would have made four, and the newly discovered stone would have made five. It was that one that has been estimated at 1,650 tons.
Interestingly enough, the heaviest known megalith was cut out in China, weighs something like 30,000 tons, but was never moved after it was cut out. One has to speculate that it was carved out already standing, beginning with the bottom cut, continuing with the sides, and finally the back to free it from the bedrock, but it’s difficult to say. Let’s see how my recollection is, we’ll ask someone who told me about it...