Could it be a small alien craft or probe or eventually a building structure or is it just an optical illusion?
If you compare the black/white images (SOL 1046) with similar images from the same area (SOL 1047) then you can see the top of the mountain and the unknown object in the black/white images, but it appears that NASA has left out this part of the mountain in the much brighter and clearer color images.
Why? There is something to hide for the public?
SOL 1046 - 2 black and white images with object on top of the mountain.
Compare SOL 1046 black/white images with SOL 1047 color images.
NASA has left out the top of the mountain in the color images.
Image below shows the triangular object what looks like (1) a small craft with windows connected to a small triangular tower or (2) building structure.
Link SOL 1046
Link SOL 1047
We recommend to check out the original large sized black/white NASA images.
Link black/white image nr.1:
Link black/white image nr.2: