Green Crystal in Granite Rock. Is is Pegmatite Granite?

[HappyTrails55]

Digging in the cracks of bedrock for gold (and getting some) I found these curious looking granite with Green Crystal in it. It's very small, the pic's don't do them justice though, curious little dinky Gems of what? Emeralds? Flourite? Tourmaline? Or is it nothing? I know there's Voids or Vugs in this granite, it's plain to see in the surrounding rock. Should I keep a watchful eye out for more or am I just wasting time? Could there be a Pegmatite Dyke Close By? Just how often are Gems found in Granite? I know they'd have to be a reasonable size to be worth anything, but does just the Presence of them Indicate that there could be a Larger Amount close?....Hope the pic's are good enough, had to put them next to some of my pennies to see what clarity I was getting...Darrell

 

Amazon Forum Fav 👍

Agony and Death on a Gold Rush Steamer: The Disastrous Sinking of the Side-Wheeler Yankee Blade - Grab it through Amazon!

[Eu_citzen]

Pretty sure that isn't pegmatite -- the mineral grains are way to small.

Can't say anything for sure, the green stuff has no tell tale signs. Can you scratch the green stuff with a knife?

Should I keep a watchful eye out for more or am I just wasting time?

Always keep an eye out for anything out of the normal -- great finds can be made that way.

Could there be a Pegmatite Dyke Close By?

Could be, but there are no indication of such in the pics there.

Just how often are Gems found in Granite?

Gems are just that -- gems. Not all that common.
But that depends on the geology -- other minerals in the same area will tell you what elements are present and what gems COULD exist there. But, well, maybe that's a more advanced geology class.

I know they'd have to be a reasonable size to be worth anything, but does just the Presence of them Indicate that there could be a Larger Amount close?

Do they? Research benitoite, bixbite.. Not all have to be big to be worth a considerable amount of $$$.
Maybe, maybe not -- just one way to find out!

If your looking for gems keep an eye out for quartz veins, vugs and pegmatites.
If your panning in the river, take it slower, harder minerals that are gems can sometimes follow a river coarse a fair distance. Any gems will usually be just over the blacksand for those that are easiest to pan. (corundum, garnet for example)

 

[HappyTrails55]

THANKYOU FOR YOUR HELP, I will keep it all in mind. Darrell

 

[kkglawson]

it looks like decomposing granite to me , worthless

 

[HappyTrails55]

Well your probably right as well but what makes the quartz in the granite turn green? There has to be a Element like Vanadium or Berilyum, Aluminum or something else that is present, don't you think? Afterall, there's still discoveries going on in the field of Geology. It's not a perfect Science. And even though there's little discoveries like what happened over 30 years ago in the Mount St. Helens when it blew (1980) and all of the pulverized rock turned into ash, certainly I'm talking about Synthetic degrees, but still the formula or the menu of the ash when heated turned it into synthetic gems. That Ash or Volcanic Scora containing all of the right elements for it to turn into "Helenite" or what some Jewelers term as "Mount St. Helens Emeral Osidianite Jewelry". ...<http://www.mt-st-helens.com/rings.html> There's other websites on it...I know a little something about Basalt/Scora Emeralds since I have found them, still impregnated in the VUGS of the Scora, but it never was enough to treat it as a profitable find, merely a curiousity, but the fact that they do occurr like this in "Situ" Naturally, interests me. But those I found years ago in the Desert. (See Pic's)...Darrell

 

[Eu_citzen]

Quartz get's it's green colour from Fe2+


I don't think you've got greenish quartz there - it is uncommon in natural conditions.
Most of what you see in the way of green quartz (Prasiolite) on the markets today is irradiated or otherwise treated.

However inclusions can also make it look greenish, but then it's not to be called prasiolite.


"Basalt/Scora Emeralds" -- is that a nick name for Olivine/Peridote?

But the host rock might be granite or something along those lines.

 

[chadrack]

I wonder if in the first set- the decomposed granite- the green might be epidote. I've seen many unakite areas where the feldspar grades to white. It could also be olivine though. In the second set of pics, I think the inference Eu made with basalt, olivine, and its gem form peridot is partly correct. Olivine is not uncommon in basalt. But then neither is chalcedony. And isn't there a bit of chlorite involved in the "greenness"? Well, if you take basalt, vugs, chalcedony, and a bit of chlorite what do you get? Chrysoprase! And chrysoprase just happens to look just like that. Also, I do not think that prasiolite occurs in nature at all. It is heated/irradiated amethest. Natural greenish quartz is generally refered to as prase. And HT, emerald is formed in some very nasty, violent, and unique conditions and basalt is relatively quiet and tame.

 

[Eu_citzen]

About the olivine/peridote, I remember reading that somewhere, don't recall where?

But since he said he was out in the desert Arizona came to mind - which is a known peridote producer.

In what mineral did you mean chlorite is involved?

Chrysoprase gets its colour from (microscopic) nickeliferrous inclusions if memory serves.

There has been a lot of discussion about if prasiolite occurs in nature or not.
Personally I'm just riding it out to see where it leads.

Good read:
http://www.quartzpage.de/prasiolite.html

Prase, had not heard of that before: http://www.quartzpage.de/prase.html

CD
I think the "scora/basalt Emerald" thing is some kind of trade/nick name for peridote/olivine and has nothing to do with the beryl. Not certain though.

 

[chadrack]

Olivines break down or alter to chloritic materials under certain conditions. Arizona is also a known producer of fine chrysoprase. I guess I made the jump from what appears to be green colored cryptocrystalline quartz to chrysoprase. I thought maybe that the alteration of the olivine might cause green coloration as the chalcedony forms. But after a quick read I see that you are correct that nickel is the coloring agent. So I wonder what to call green chalcedony? How about HappyTrails chalcedony. There may already be some floating around in the Arizona chrysoprase market! An expert I am not, but I do learn things as I embarrass myself on the internet. Also, after the aforementioned reading, I think I will ride out the prasiolite question with you. In addition to your links, I saw a reference to a possible prasiolite occurance in the Four Peaks region of Arizona. As HT said, geology is not a perfect science and I will add that a little chaos in the gem trade is nothing new. I still think it is probably epidote in his crumbly granite though!

 

[Eu_citzen]

CD,

I thought it was basalt (consisting mainly of pyroxene) that altered to chlorite, epidote and similar while Olivine alters to Serpentine? Might depend on what kind of alteration maybe.
I'll have to look it up.

I see lot's of Chlorite schist around here in TIB (Trans-scandinavian Igneous Belt) which I think is the result from intrusive rocks (felsic rock) either directly or indirectly from metasomatic alteration of Basalt dykes.

Can't olivine contain small amounts of nickel? I think it can.
Let us think the chalcedony and hydrothermal fluids are concentrated in a vug in a mafic host rock.
The "hot" solutions could affect(/Alter?) the host rock which surrounds the vug?
I'd bet it would -- to colour the chalcedony we only need to pick up trace amounts of nickel.


I don't know what to call green chalcedony, green opaque chalcedony would be easy to classify as Jasper.
Otherwise I dunno.

I also did not know Arizona produces green chalcedony/Chryoprase, cool!
And when it comes to geology I guess no one is an expert, I to am just an amateur.

I agree, epidote is a possibly, fluorite is also a candidate.

 

[kuger]

We have been finding green crystals for years,out of the ground green......I will take some pics,always wondered what caused it?