https://en.wikipedia.org/wiki/Coefficient_of_restitution

1 would be a perfectly elastic collision

i guess it the bouncing effect
and rubber must have like 0.9 when tungsten 0.1
the carbon ?

so 2 brick of the same mass and restitution will share the colision speed in half in the opposite direction

and this why every material have the 0.1 value...

is their a relation with the unsnaping ?

Rubber was bouncy but was changed in the newest updates.

for reasons i guess
thanks for the clarification
i will take a bit of time for select the answer used for solution

tungsten carbide 0.73 to 1.13
stainless steel 0.63 to 0.93
aluminum alloy 7075-T6 0.75
glass (soda-lime) 0.69
cast iron 0.3 to 0.6
tungsten 0.37
aluminum alloys 3003 6061, 7075-0 0.35
copper 0.15
aluminum 0.1
lead 0.08
silicon 1.79
silicon nitride 0.38 to 1.63
silicon carbide 0.47 to 1.31

not what i expected
no idea of what aluminium or what silicon type we use commonly
im sure that tungsten carbide is the hardest tool used for drills