Spheres coming from bedrock?

Joe Knapp wrote:
JPL has posted new raw microscopic images of the spheres in situ, embedded
in the outcrop--pics taken 4am PST Sunday (sol 15):

http://tinyurl.com/2boql

http://tinyurl.com/2rtga


Joe

Every time a see a yet closer image of the outcrop at Meridiani Planum,
I hear this Krusty the Clown voice in my head saying: "What the hell was
that?!?!?"

I've just about given up speculation on the origin of this stuff. But
not quite...

Close-ups like this:

http://marsrovers.jpl.nasa.gov/galle...2P2933M2M1.JPG

continue remind me of textures and fabrics I've seen in travertine and
sinter deposits. The first Navigation Camera images, while still on the
lander, looked like bedded clastic rocks (e.g. sandstone). As the rover
got closer, both the PanCam and NavCam images looked more like ratty
welded tuff (volcanic ash). Now, when the rover is right up against the
rock, it looks like a chemical precipitate! And the roundy things are
definitely a lag weathered out from whatever this stuff is.

It will be nice to get some close-up spectrometry for some idea of
composition. No one has said carbonate or silica out loud yet, but I
wonder...

If the spheres are the source of the hematite, what could the host rock
possibly be?
---
Tim Demko
http://www.d.umn.edu/~tdemko