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I was out hiking in the Vulture Mtns of Arizona, doing some prospecting for future gold areas and found this rock out cropping.  I broke off a piece and took a picture up close.   All the rocks from the outcropping were intruded with these black shaped minerals.  What do you think it its, quartz with Magnetite?   I'm curious to learn the process of how these minerals formed..

Rock Sample.jpg

 

Edited by Andyy
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Black Tourmaline Andy. More accurately Schorl. Lots of it in the LSD and Vulture areas. No commercial value but I know some eastern rock clubs that treasure the stuff.

Schorl is always black but there are others in the Tourmaline group that can show blackish. The most common being Dravite.

Edited by clay
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Probably not Quartz. More than likely the whitish rock is Pegmatite. Specifically Albite which would make the rock an Alkali Feldspar - quite often mistaken for quartz but a very different composition. Feldspar is the mineral that degrades to fine grained clay.

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7 hours ago, clay said:

Black Tourmaline Andy. More accurately Schorl. Lots of it in the LSD and Vulture areas. No commercial value but I know some eastern rock clubs that treasure the stuff.

Schorl is always black but there are others in the Tourmaline group that can show blackish. The most common being Dravite.

Crystalized specimens can bring big bucks.

This is a little off topic but I heard a few years ago that a massive 3ft long beryl crystal was found somewhere in the LSD area. Don't know if it's true or not. Perhaps someone here can verify.

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11 hours ago, clay said:

Probably not Quartz. More than likely the whitish rock is Pegmatite. Specifically Albite which would make the rock an Alkali Feldspar - quite often mistaken for quartz but a very different composition. Feldspar is the mineral that degrades to fine grained clay.

ok.  I didn't think it was tourmaline because of the shape.  Interesting.

As for Pegmatite, I originally thought it was a Pematite because it contained large minerals, but did not realize that the host rock was the Pegmatite or Albite.  And the white part of the rock does appear to be more fine grained.  So this makes sense.

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5 hours ago, Morlock said:

Crystalized specimens can bring big bucks.

This is a little off topic but I heard a few years ago that a massive 3ft long beryl crystal was found somewhere in the LSD area. Don't know if it's true or not. Perhaps someone here can verify.

LSD is known for very large crystals in it's pegmatites. Some nearby areas produce exposed single crystal bodies upwards of 60 foot long. It's entirely possible a 3 foot Beryl was found.

Crystal values are often based more on buyer perception than any actual rarity. Markets are driven by perception. Schorl in Albite is far from being rare but if there are willing buyers there will be a market.

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Dang it, Barry.  I had my resignation letter all filled out.  Way to ruin a guys dream :grr01:

But seriously, thank you for the information.  Now at least I know what I am looking at.. Next step is to do some research on pegmatites to determine what this can tell me about this area.  

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On 4/4/2017 at 11:56 AM, clay said:

LSD is known for very large crystals in it's pegmatites. Some nearby areas produce exposed single crystal bodies upwards of 60 foot long. It's entirely possible a 3 foot Beryl was found.

Crystal values are often based more on buyer perception than any actual rarity. Markets are driven by perception. Schorl in Albite is far from being rare but if there are willing buyers there will be a market.

The crystal I'm referring to wasn't in matrix. It was free standing on matrix. Supposedly it sold for $50,000. That was the rumor I heard but never could verify it.

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