It’s difficult to tell if this part actually belongs to the iPhone 6. It is possible this is a frame for the upcoming Amazon Fire Phone which has a similar structure and camera components on all four corners. The frame also appears less round and thicker than the previously leaked iPhone 6 frames.
These aren’t the first such leaks in recent months. We’ve seen other photos of the front and back of the 4.7-inch phone from last month. The part shown in this new photo seems to fit with those components.