[meteorite-list] What are those blueberries on Mars?

From: (wrong string) ørn Sørheim <bsoerhei_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:22 2004
Message-ID: <200402131609.RAA19852_at_mail46-s.fg.online.no>

Hello List,
I guess you all have seen those pictures coming from Mars at the
the Meridiani Planum/Opportunity site.

Embedded in, and eroding out of the bedrock in the sidewall of the
20 m crater where Opportunity is located, are those <5mm perfect
spherical stones.
They have a different colour than the finely layered matrix they sits in.
The geologist Steven Squyers said that there were 3 theories about them
among the scientists at JPL - the 3rd one, by now almost discarded:

1) They are concretions in the layered deposits, that formed slowly
 after the deposists had been made, probably by water circulating through
 them and slowly crystalizing.
2) They are balls made from molten material flung up in the atmosphere
 either by volcanic eruptions or large crater forming impacts.
3) They are volcanic 'lapilli' formed as growing spherical balls from
 ash coming out of an erupting volcano. Since these small balls (blueish)
 as photographed by Opportunity, has a different color than the deposits
 they are located in, this seems less likely.

So what are your theories, any thoughts?
Another theory: Could they be rock fragments rounded by the movements by
the wind in fine deposits through millions of years at the surface?

Link to picture:
http://photojournal.jpl.nasa.gov/jpeg/PIA05235.jpg
http://photojournal.jpl.nasa.gov/targetFamily/Mars (More pictures)

Regards,
Bjørn Sørheim
Received on Fri 13 Feb 2004 11:09:19 AM PST