how to determine how much weight a wall can hold

Greetings, My husband and I are looking to install a stone veneer (Lowes desert quartz ledgestone) wall above our fireplace. The wall above the fireplace is offset approximately 8" from the main living room wall (total size is 6' x 6') and we are unsure as to whether it is capable of holding approximately 500 lbs of stone. We have identified the studs but are unsure if they are structurally secured to the primary wall frame or if this is just an aftermarket facade. We poked a small hole in the drywall next to one of the studs and saw that the studs are only 2x2's and are not connected to the wall behind them. If anyone has any advice, we'd greatly appreciate it. I'm attaching a few photos of the fireplace. We are looking to put stone over the diamond patterned portion. Thanks!Attachment 37363 (http://www.doityourself.com/forum/attachments/walls-ceilings/37363-how-determine-how-much-weight-wall-can-hold-20140829_213200_resized.jpg)Attachment 37364 (http://www.doityourself.com/forum/attachments/walls-ceilings/37364-how-determine-how-much-weight-wall-can-hold-20140829_214853_resized.jpg)