here is piece number one - It's either rainforest green or jurassic granite. It's 18 inches x 3 ft. It probably weighs about 100 lbs. This is how we installed it:
Ben put screws into the studs of the wall
He drilled corresponding holes into the stone. Then a whole mess of Liquid Nails
Then we stuck it to the wall in the guest bath. And said a silent prayer.
The other piece is a 4' x 4' piece of marble in the entryway niche. Hooks installed into studs.
The stone company epoxied the 2 x 4's to the back of the marble and Ben drilled holes and epoxied in the hooks onto the wood. Next he added lighting for effect.
This piece is probably over 200 lbs. But with the help of a friend, it made it onto the wall. But before it made it onto the wall, it suffered a crack while picking it up. even though we have picked it up and down a number of times prior. Which is probably what weakened it.
All in all, I think it looks nice and appears to be quite sturdy. Of course this is a concern. I do wish it was about an inch or two recessed into the wall. Right now it is suspended about 5 inches from the wall. But first we have to get the crack fixed.