Set the rock on a flat surface and roll it around. Find the most even place near the center where the rock balance has near equal weight on the right and left side.
Wrap the rope around the dividing point where the center of balance is on the rock. Bring the slack from the end so there is at least 15 inches of rope on the end from the wrap around the rock.
Twist a loop into the end of the rope.
Bring the main line over the twist and form another coil so you have what looks like a pretzel in the line.
Take the twist from Step 3 and push it through the Step 4 coil. You now have a long loop sticking out from the main line.
Wrap the loop around the rock and place it next to the first wrap on the rock. Pull tight on the main line to lock the knot, thus securing it to the rock.