I think the spherules in the rock have quite a lot of external structure. I am particularly interested in the recent spherule from http://marsrovers.jpl.nasa.gov/gallery/all/1/m/086/1M135817872EFF1407P2936M2M1.HTML.

It is in shadow so it doesn't immediately stand out, but it is very clearly grooved (or folded, it's difficult to tell). On the lower exposed surface there is a coating that looks quite organised, although the image is not quite big enough- where you see it side on it has an almost furry effect. It dosen't look like dust anyway.

I tend also to agree that not taking a good hard look at the stalked blueberries is rather selective; at the vey least it would provide some insight into how the rocks are being weathered.

Andrew