A cellphone made of marble is bound to be heavy. It’s what your rich caveman dude would be making deals on if cavemen had such devices. There are some advantages to stone cellphones. It can be used as a weapon should you be attacked, it will survive drops from super high and you can carve pretty primitive pictures on it even.
Sadly this is just a concept. The Mobiado CPT001 is not available. The shipments would weigh too much for trucks to haul anyway. Sorry Fred and Barney.