Adding masonry mass to stove to stock heat

Hi there, my first post as you see so I would like to say hello to forum users.

I would prefer to build a masonry stove but since it won't be on the ground floor I won't because of weight issues.

In order to get some of the advantages of this type of heating I would like to add mass to a stove just to store heat. Here in France you can buy a cast-iron firebox with fins which is usually built into rather ugly fireplace/chimney units sold in big DIY stores.

What I wish to do is build a heavy rock "wall" around and on the stove body for max heat take-up and storage. Weight will probably be 800 lbs vs 5,000 for masonry stove.

I asked in a store about this and they were unsure about what was obviously a strange concept to them. I will contact manufacturers too, but would like to know if anyone has done this and if they are pleased with the result/ what they might do differently - the usual questions in fact.

Unusual questions might be if there is any difference between different types of stone for absorbing and giving back heat ( is there a scientific term for this ? )

Look forward to your replies

Alpineskier,
You sound like an ideal candidate for a rocket mass heater. Because of the internal stack you can run the exhaust horizontal through a masonry bench and spread the weight out so the floor can handle it. Check out rocketstoves.com ,you can download the book!

Soapstone is the choice of two well known U.S. stove companies .