# For which solid is the speed of sound highest at 20°C?

I am seeking the solid with the maximum possible speed of sound . At the begining I though it depended on the density of the solid but at the same temperature the element ruthenium give a higher speed for of sound than the denser element osmium. The difference is about $1000 \mathrm{m/s}$ at $20\mathrm{°C}$.

So can someone tell where and how can to find the solid in which the speed of the sound is the highest?

I emphasis that I am not asking only for the elements of the periodic table, it can be any solid material, even a mixture of materials.