I bought a beautiful Woodsong Garrard 301. It came with a Tenuto gun metal mat.
Think it added several pounds to the machined Woodsong platter.
The Tenuto mat was outperformed by a Oracle acrylic mat. Which is now outperformed by my current titanium impregnated Oyaide mat.
My understanding about mass of a platter is highly dependent on the overall design of the motor and TT.