|
Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
|
Post by Sabre52 on Jun 30, 2011 16:43:00 GMT -5
Carlos: I think Australian Print Stone and that Indian Paint Stone from death Valley are true argillite. They are both sort of silicified clay mud type materials and I've seen them classified as argillite by geologists. They are sort of a fancy silica rich metamorphosed siltstone or mudstone. The NW picture jaspers are highly silicified volcanic molten ash flow mud that that supposedly has flowed into pockets and seams in molten ash or lava and been compressed and contorted to various degrees. I don't know if argillite is a cold deposit or a molten one. I suspect it is a cold deposited sedimentary rock that has undergone lithification with various amounts of silica. Many clay types are composed all or partly of volcanic ash ( bentonite for example) so I guess the picture jaspers which are sedimentary types could be called argillite too but have a different genesis involving volcanic action. I'm not a geologist so I may be way off on this.....Mel
|
|
|
Post by Rockhobbit on Jun 30, 2011 17:49:22 GMT -5
Wow Mel, I am in awe. I learn so much from your posts! To heck with lapidary classes, I just read your stuff! LOL
|
|