I have recieved the ball and i weighted it, it came out on approximately 26 grams. I also measured the diameter and this is 2,9-3,0 cm.
So when calculating the volume we can use the 4/3 x Pi x R(Radius)^3 formula. This would be 14,137 cubic centimeters. The density of limestone is between 2,3-2,7 that of quartzite 2,6-2,8 and marble 2,4-2,7 gr/cm3.
The weight and diameter would sugest a material of 1,85 gr/cm3
This is a very pragmatic view and too hard on my brain at this time of day after a train journey of 6 hours or so...
Attached are pictures of this ball.
Best as always and sleep well my friends.
