Nice stone fireplace...Can I keep it?

Hello. I wasn't sure if I should keep adding on to my other thread or not since, this is a new topic. Anyway here it is: I'm shooting for STC of 63 (according to the chart below) because I've got neighboors 25 ft away, and will be tracking loud drums late. I will be floating the floor,walls and ceiling. I would love to keep this stone fireplace (only because of it's looks/vibe that it will give the tracking room) It seems to be basically limestone cemented onto the drywall. Obviously this is a huge amount of mass, but will it flank into the rest of the oustide leaf enough to defeat the purpose of floating the rest of the room? My other plan is to just build around it. That won't be too hard, but losing the fireplace will be quite saddening. Also If I can keep it, I realize I would have to seel it up somehow to keep sound from getting in and out thru the chimney. Thanks for any suggestions! here's my first post about Mass/Air/Mass http://www.johnlsayers.com/phpBB2/viewtopic.php?t=5993

If you seal it, make sure you seal the bottom, where a fire would normally go. Don't just go up on the roof and seal the top... that'd be very bad. Someone buys the house after you and starts up a nice cozy fire on a cold night, next thing you know the whole house has burned down. :) So don't do that. You can't keep the fireplace open as it is. You might as well just cut a big hole in your studio, because that's what it is.

and stuff it with fluffystuff... to kill resonance/drumskineffect