Agates, Onyx and ancient cave questions...

[fuzzy-hair-man]

green granite is apparantly possible - there's a place in Australia where oxidizing iron has lent granite a green color....

Do you know where in Australia? Just curious...

[hewhocaves]

http://www.pir.sa.gov.au/byteserve/mine ... ranite.pdf

i don't know where the place is. maybe you can figure it out from the .pdf file.

[fuzzy-hair-man]

Thanks, Padthaway in South Australia's South East Region. The Area also has a lot of limestone and nearby Naracoorte caves(World heritage listed, I think...) is where a lot of important fossil finds have been made of Giant Marsupials (Wombats, kangaroos koalas etc) I was around that area ~ 3 years ago didn't know about green granite though. I didn't think there would be much granite in that area to tell the truth

[bigalpha]

yes! shiney rocks! I'm in.

Teresa -- while you cannot definitively say that the coloring of a rock is from one element/cation -- can you say that it's most likely from a certain element/cation? Or maybe, from a higher concentration of element/cation than other impurities?

I think it would be more that there are 'typical colors'--except in the case of gemstones which are defined by their color--for example corundum by any other color is sapphire, red corundum is ruby, or amethyst--defined as purple quartz.

Colors can fool you though. Being a mean TA, I would give kids green fluorite and basalt with big pink phenocrysts for their tests. Not enough of those zingers to fail a student, of course, but one or two to humble the know-it-alls..

Now, if you ID a rock by a suite of characteristics--color+texture+hardness+any other weird characteristic you are much safer.

Our Mineralogoy professor did that to us!! It was horrible. There was like 3 samples of fluorite, but two of them looked like other stuff. It was crazy.

[graveleye]

there is some green and pink "granite" about in places like North Carolina. I have a few specimens of it. Called unakite I believe.

I live only a few minutes from Stone Mountain here is Georgia. No caves, but its still one cool monadnock. The back side is pink and the front side (with the carving) is granite-gray. I used to think the back side was pink because not as many people looked at it

[graveleye]

oh by the way.. PM me your address if you want shiney rocks

I'm not a stalker.. promise!!

[Teresa]

Unakite has granitic texture, but it's not. I know that stuff.