Jebel Arkenu

It does appear to be volcanic. My first stab is that this is part of the Tibesti volcano complex, but Tibesti itself is a bit further west (see http://googleglobetrotting.com/info.php/mid/4815).

Some further info about Tibesti:

http://en.wikipedia.org/wiki/Tibesti_Mountains

http://volcano.und.nodak.edu/vwdocs/volc_images/img_Tibesti.html

Followup -

I think the area is called "Al Uwaynat desert". This map has a spot labelled "Al Uwaynat" that corresponds to the location of the rock formation:

http://www.lib.utexas.edu/maps/africa/libya_pol93.jpg

There's a photo file with the same name here:

http://www.archipress.org/images/strategie/uwaynat.jpg

More info:

http://gisaf.sil.at/uwaynat.html

Fascinating expedition accounts (they spell it "Uweinat"):

http://www.fjexpeditions.com/frameset/nov04.htm

And, finally, I found the names of the rock formations. Map id 3477 is centered on "Jebel Arkenu":

http://www.fjexpeditions.com/frameset/g_arkenu.htm

Immediately to the southeast is "Jebel Uweinat":

http://www.fjexpeditions.com/frameset/uweinat.htm