The Obelisk in the middle is about one and a third Dookus tall. That's (4/3) x (height of Dooku). Dooku was noted as 1.9 meters tall earlier in the thread, so that means (4/3*1.9) =2.53 meters.
The Obelisk in question is about half a Dooku wide at the bottom. So that's 1.9/2 or .95 meters.
(1/3) (.95^2) (2.53) = .076 meters cubed.
Having found the volume (in meters cubed) we must now make a reasonable guess about the density. Similar materials on earth (Marble, Obsidian) have densities of around 2.6 grams per cubic centimeter, or 2600 kg per cubic meter, or 5,730 pounds per cubic meter.
Multiplying the volume (in cubic meters) by the density (mass per cubic meter) gets us an answer to how much mass is in play. Assuming normal Earth gravity, this is our answer for weight. Thus:
([.076] Cubic Meters) X (5730 lbs / Cubic Meters)
= 4361 [Lbs]
= 2.18 [Tons]
This is for the larger size of pillar. Am I just biffing the height comparison? How are you making it to 24 tons?