Chat Transcript - 23-24 Dec 2011
Łukasz Niedzielski - jummmmi:) Look on colours in different places different colours and this black (bitumic) pseudomorph. Great piece and great picture:) was in my hand:D Merry Christmas:)
David Rix What - exactly is a bitumic psudomorph?
Łukasz Niedzielski - I don't realy know:D but one saying that bitumic pseudomorph is replacing agate by organic substans/matter. What You think?:)
David Rix - To be honest, I have no idea this time! Those angular shapes are actually pretty familiar but as holes! In this case we have a muddle of quartz and black stuff. I think we will have to throw this one out to the more scientifically minded! Any ideas folks?
David Rix - Also, interesting the way the crack at the bottom left has leached so much colour out of the agate around there!
Łukasz Niedzielski - I think this black stuff is organic substance, but i'm not an expert:) I just love them:)
Łukasz Niedzielski - idd, left side is so cool - some white ribbons changing to different
Jason Hinkle - Sometime the "negative casts" or the angular shapes you see could very well be calcite and or aragonite. I see this commonly in Fallen Tree eggs. I believe the calcite is in place first, then the agate fills in around it. Somehow over time (maybe the silica solution turned acidic) and rotted the calcite out and left the holes you see.
David Rix - Yes - these calcite holes are very common in Felsenschlag, Esterel etc around Europe as well - in this case though something further seems to have happened to the agate that surrounded it since it has morphed or stained into this weird black texture. You cant see it clearly in the pic because it is too small, but there are distinct fortification lines within the black. Dunno whether the rot corrupted the agate, whether whatever was there before caused the agate to form like that originally or if something else came along later - all good fun speculation!
Jason Hinkle - Interesting - Yes after looking closely at your expanded photo I can see the black agate. My first glance I thought it was just a hollow hole. That is interesting...
