I did not know whether to open a new thread to contain all of the things that we might find on this rock. I also wanted to mention the Apollo photo number in the title so that people could find it later if they needed to.
Another thread showing Iceman's mask he has found on this rock is here along with some discussion how to use Google to find photos and how to download etc.
---------------------- This is what appears to be a small flat disk on the rock as shown in AS17-140-21438. I have given the context (circled). It is near to one of the cross-hairs which makes it convenient to find, but it is fairly small.
Images in this sequence are all taken from the colour tif file here Thanks to O'Brien for finding the tif file which is 46Mb. The first image is taken directly from the tif file and has not been changed. The disk itself is at 7 o'clock from the cross-hair, fairly close to the bottom left hand border of the extracted photo.
For illustration purposes only, I have included other photos I have made from the different parts of the original colour image. These are labelled 'red/green/blue' and are processed by me from the colour tif image and each colour channel has been made into a greyscale black and white image and then the relevant area shown.
As you can see this may highlight or emphrasise other parts of the image due to reflecting the light wavelengths in a different way.