I don't know about this weight at all. It does look as if there are silver chloride salts used to create some of the surface colours, but that doesn't mean it's Mdina.
If it is, I would think it's quite a late/recentish piece, not an area I'm familiar with.
The very conical shape is not one I recognise, it's surface decorated - I'm more familiar with when colours were melted in the pot, the base does not look like any I've seen.
Sorry not to be of any use at all.