I think it's a fossil?

[azrhound]

Hi everyone I found this stone while hiking in the Phoenix Mountain Reserve today. I think it is a fossil but I am not sure. Please let me know if you have any idea.
Thanks,
Tom(AZrhound)

[azrhound]

Here is a close-up of the same rock.

[gemlover]

Looks like a radial crystal pattern (actinolite or tremolite are examples). There are several white minerals that can have this pattern. Thus, the questions:
How hard is it?
Does it show cleavage?
Does it have a fracture?
Does it show a crystal shape?
What color is the streak?

Basic mineralogy identification questions, identifying from a picture can be very inaccurate.

[amythestguy]

Gemlover you say "identufying from a picture can be very inaccurate" but you did a good job on PEACHY AND MYSTERIOUS identifying dolomite. Nice job

[gemlover]

lucky guess, the only carbonate that I know of that doesn't fizz in acid is dolomite.

[gsellis]

It is a type of crystal. I remember reading about it, but I cannot remember the name. Something like "selenite" or some such spelling I think, but I could be reallly off.

[azrhound]

Thanks for all of the info. gemlover I'm not sure how to do all of the testing to get you the answers to your questions. I would be happy to send you a sample to test. I found another large piece with lots of crystals and I just wanted to share some photo.



Thanks again.

[gemlover]

not too big a piece please

Rasmussen Gems and Jewelry
P.O. Box 1663
Easley, SC 29641

[amythestguy]

Thats a real cool piece you found azrhound!

[eriktheawful]

Does it have a greasy feel like talc. Pyrophylite sometimes forms radials like that. Can you scratch it with your fingernail?

[gsellis]

Try Wavellite.

[Riviera]

Not sure but looks like Scolecite we find here in the quarries.
Denny

[arappaho]

Thanks for the heads up on Scolecite, Denny. That's another one I've never heard of before.
But I'm going to have to throw my hat in the ring for Pyrophillite on this one.
Joe

[azrhound]

gsellis,

I think you are right!! I did a google image search for Wavellite and I saw some picture that are very similar to my crystals. I am sending gemlover a small sample and he is going to test it. Then I will know for sure.

Tom

[eriktheawful]

Ya the schisty look of the host leads me towards the pyrophylite guess

[azrhound]

O.K. I went to the library and I pick up a book called "Rock and Gem" by the Smithsonian Institution. I now have to agree with everyone that said Pyrophyllite.

Thanks to everyone that had an input. I hope that I can learn a lot with this book and the others that I pick up, and I hope to be able to help other.

Tom (azrhound)

[gemlover]

Looking forward to seeing the real mccoy (and if I were a Hatfield that might be dangerous) and I will let you know when it arrives, the off to the work space to have fun. In Rock and Gem, if you look a few pages further, you will find several other minerals with similar radial crystals. As I said, looking forward to seeing the sample and testing it. This is like a murder mystery for me, putting the clues (data) together and coming up with the name (mineral, nor murderer).

[gemlover]

:)OK thank you Tom for the sample, the trickeries of photography become apparent, the underlying green color of the schist and the radial crystals is not obvious in the pictures. the radial crystals and underlying schist is primarily CHLORITE. Please excuse my inability to manipulate the text, but Pyrophyllite is too soft, however, it is in the same group of minerals and the two have almost the same chemical composition.

Pyrophyllite -- Al2Si4O10(OH)2 (Serpentine Group)
Chlorite -- (Mg,Fe)6(AlSi3)O10(OH)8 (Mica Group)

They are both Phyllosilicates
Properties of Chlorite:
Color and Luster: Light to dark green, black, pearly, vitreous, dull
Hardness: 2 to 2.5
Cleavage: Perfect, one direction

Now here is the kicker, chlorite pseudomorphs into other minerals crystal structure patterns during the metamorphic process of formation, so the radial crystal pattern could be an impression of the previous mineral there, probably pyrophyllite.

This is a beautiful specimen of a Chlorite Schist. This is found in multiple locations near your home, Tom. See the mineral description with a location map (zoom in to Arizona, there are at least 18 mines near your home).

www.mindat.org/min-1016.html

By the way, Chlorite is not shown in Smithsonian's Rock and Gem, although it is mentioned in narrative in several places. I would also suggest "National Audubon Society Field Guide to North American Rocks and Minerals" as a good general reference. The mindat.org website is an excellent source of information also.

Thank you for the opportunity to see and handle this specimen, I have not seen this good of a sample in many, many years.

John

[arappaho]

Thanks for the analysis, info, and closure, John.
Appreciate it very much, Joe.