Martian Hematite in the Berry Bowl

New Scientist reports from the Lunar and Planetary Sciences Conference, now going on in Houston, that the tiny "blueberry" spheroids in the Martian soil and rock look like hematite. The Opportunity rover determined this by examining a small hollow where the spheres were gathered in a tight bunch, suitable for its instruments. The berries gave a strong signal corresponding to hematite while the surrounding soil did not.

This raises as many questions as it answers. The answers are: Yes we have found the hematite, No the berries are probably not tektites (as I suspected) and No they aren't volcanic. Next questions: Are they ooids or concretions? What is at their centers? What accounts for their shiny surface? Why are they so small?