Hello, Yousef and List -
Your rock with the red circles appears to be a vesicular basalt,
with calcite or another carbonate mineral filling the vesicles. The
carbonate minerals grow from water solutions, like groundwater. The
carbonate minerals start as a little tuft of crystals, on the wall
of a vesicle. As the crystals grow, the tuft turns into a
hemisphere of elongate crystals radiating from the starting
point. If the water solutions change composition, the carbonate
minerals change composition too. The red bands are where the
original carbonate mineral contained more iron, which has now
oxidized to bright red hematite.
This kind of alteration is fairly common in terrestrial
basalts. I've done some work on alteration like this where
the carbonate mineral is siderite (FeCO3) and magnesite (MgCO3),
but the most common kind of filling like this is calcite (CaCO3).
Here are two references for you.
<http://www.lpi.usra.edu/science/treiman/spitscarbs.pdf>
<http://www.lpi.usra.edu/meetings/lpsc2002/pdf/2057.pdf>
Cheers.
Allan
Allan H. Treiman
Senior Staff Scientist
Lunar and Planetary Institute
3600 Bay Area Boulevard
Houston, TX 77058-1113
281-486-2117
281-486-2162 (FAX)
-----Original Message-----
From: M Yousef [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 28, 2003 3:42 AM
To: [EMAIL PROTECTED]
Subject: [meteorite-list] Red Circles
Dear All;
When I cut one of the rocks I found white clasts of irregular shape (mostly
spherical), but what was amazing is that inside some of these clasts there
was well defined red circles. Any Idea?
http://www.alifyaa.com/meteorite/rc/
Mohamed H. Yousef
----------------------------------------------
_________________________________________________________________
Tired of spam? Get advanced junk mail protection with MSN 8.
http://join.msn.com/?page=features/junkmail
______________________________________________
Meteorite-list mailing list
[EMAIL PROTECTED]
http://www.pairlist.net/mailman/listinfo/meteorite-list
______________________________________________
Meteorite-list mailing list
[EMAIL PROTECTED]
http://www.pairlist.net/mailman/listinfo/meteorite-list
