Re: [meteorite-list] Aswan Rock - Opinions?

[N Lehrman]

Jeff & list,   I've spent my career with rocks like that!  It is a hydrothermal breccia from a low-sulfidation epithermal vein system.  You'll notice that some of the clasts have quartz/chalcedony hairlines healing jigsaw-puzzle breccias (pieces would still fit neatly back together, not jumbled or significantly displaced).  This is hydraulic fracturing that forms as fluid pressures exceed lithostatic pressures, just before a hydrothermal explosion.  Once the system cracks and explodes, fluid streaming does jumble and rotate most of the clasts.  Your rock likely contains anomalous amounts of As, Hg, Sb, and quite possibly, Au and Ag. The rounded exterior is simply from erosion and water transport.  From the photos I can't tell for sure what the clasts are, but I would guess they are rhyolite (a common associate of this style of mineralization).    Merry Winter Solstice and a Happy New Orbit to All,   Norm Lehrman (http://TektiteSource.com)     ----- Original Message ----- From: Jeff Kuyken To: Meteorite List Sent: Friday, December 12, 2003 2:38 AM Subject: [meteorite-list] Aswan Rock - Opinions? Hey all,   When I was in Egypt in October, I jumped onto a young half-trained CCRRAAZZYY camel and headed out into the desert. Among a few rocks (mostly fossils) I found an interesting stone which was nothing like the others in the area. I don't think it is a meteorite but it does look like some kind of breccia. It is a broken quarter sphere in shape and the photos are of the two broken surfaces. I'd appreciate any opinions on this one. The links are:   http://www.meteoritesaustralia.com/images/Aswan 1.jpg   http://www.meteoritesaustralia.com/images/Aswan 2.jpg   Cheers,   Jeff Kuyken I.M.C.A. #3085 www.meteorites.com.au