Announcement from Planetary Science Research Discoveries [PSRD]
New article online:
Mars Crust: Made of Basalt-- Chemical analyses of rocks on the Martian surface indicate that the Martian crust was built of basalt lava flows not much different from those on Earth.
FULL ARTICLE at:
http://www.psrd.hawaii.edu/May09/Mars.Basaltic.Crust.html