Boulder masses

I couldn't help but calculate the masses of various boulder sizes, with reference to damming the tunnel in Cantona. I used 2.75 g/cm3 for density. This confirms that, say, 5 to 8 characters, working together, can lift a 3-foot diameter boulder.

Diameter of granite sphere (boulder), feet	Mass, lb.	Mass at half diameter, lb. (1/8 orig. mass)
6	8,807.0	1,100.9
5	5,096.7	637.1
4	2,609.5	326.2
3	1,100.9	137.6
2	326.2	40.8
1	40.8	5.1

Perhaps we need one more file on this site to archive game mechanic stuff like this chart, the one I found for falling items as weapons etc. It's a little cumbersome to find these articles again within all the chaff.