Before

Black and White

My first step with this photo was to make a b&w version. Before I converted to grayscale in camera RAW, I increased the exposure, straightened and cropped the image. After converting to grayscale, I worked on increasing the contrast by adjusting the black and white points. I ended up with tiny spots of clipping, which I left because they aren't noticeable, but the overall black and white balance looked good. I did pull in the shadows and highlights a bit before increasing the clarity to give some mid tone contrast to the stone. Finally, there were a few spots on the original (I think they are actually birds and perhaps a stump in the water). They stood out even more in b&w and distracted from the main composition so I removed them using the healing brush. The longer I look at the picture the more I think that the con trail could also be removed to improve the composition. The straight line in the sky draws the eye.

Duotone

As a bonus, I imported the image into photoshop and turned it into a tritone: black 404 warm gray 401 warm gray. I like the b&w, but I think this version gives a better impression of the warmth of the stone. Then I had to remove the con trail!