# Ore identity question



## sfuller5 (Jun 4, 2011)

Recently discovered a large vein on our gold mining claims in Alaska. The vein is a about 15 feet wide with bands of the silvery colored metal wired throughout. Also looking for a reputable assayer in the Ak region? 

Thanks for any advice,

Steve


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## sfuller5 (Jun 4, 2011)

More photos of ore


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## sfuller5 (Jun 4, 2011)

What Ive done so far:
Roasted & crushed to 30 mesh & panned about a hand full of the rock. There is a large amount of heavy silver colored metal left in pan. No visible gold. About 10% of the metal is magnetic. I took 400 grains (just under an ounce) of the metallic substance (including the magnetics) and most of it digested it into about 1fl oz of AR. I heated the AR for approximately 30 minutes. After 24hrs the solution has turned a reddish brown. I filtered off a large amount of white colored goo. I have saved the white substance that I think may be Ag / Pb / Hg

I did a stannous check w/ q-tip on the remaining AR solution and it stays primarily yellow, but leaves a very minute purple stain. After researching a thread about exposing the white substance to sunlight, it seemes the quickest way to see if its silver.

Researching the geology of the region of this deposit revealed the following info:

Anomalous regional stream sediment surveys conducted by USGS determining high concentrations of: 

Copper, Lead, Zinc, Silver, Arsenic and Molybdenum 

- Studies show rocks in the area are enriched in Copper, Iron and Gold 

- Mineralogical studies have identified: chalcopyrite, malachite, azurite, bornite, chalcocite, quartz and epidote 

A fellow miner had a spectrum analysis done on his black sands revealing the presence of the following pgms: Rh, Pt, Pd

I dont recall the exact amounts of the analysis but it was in PPM of each group. 

Any help or suggestions as to what I should do next would be greatly appreciated.

Steve


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## shaftsinkerawc (Jun 4, 2011)

How long did you roast it, how high & with what if you don't mind me asking? Also did you roast before or after crushing. Also you probably need to crush your material finer. UAF Fairbanks has a handheld XRF if you're in the area. I've got a bucket crusher and can get it down below 100 mesh if you're in the area of Fairbanks. Looks interesting. Have a great day. awc


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## Militoy (Jun 4, 2011)

The metallic areas have the appearance of an iron sulfide of some kind - and the red staining could be iron oxide - but the deep red color puts me in mind of cinnabar. You might want to be cautious of breathing the fumes while roasting, until at least after you have the material assayed.


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## shaftsinkerawc (Jun 4, 2011)

The arsenic requires safety measures as well. awc


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## sfuller5 (Jun 4, 2011)

thanks for your input. I'll contact uaf to see if there accepting samples. I heated a small piece of the rock outside in a metal pan until red- hot with a mapp gas torch until it was red-hot for about 10 minutes before crushing. I'll find a better (safer) way of doing this in the future.

Steve


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## shaftsinkerawc (Jun 4, 2011)

There's ALS and Alaska Assay both in Fbks. If you have a sample you want crushed let me know. If you've got enough sample I'd like to get a piece for slabbing. Have a great day. awc


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## Richard36 (Jun 11, 2011)

Hello sfuller5,

Sorry it has taken me so long to provide my input.
I was somewhat curious as to what all others would say before I posted.

As far as I can tell, The main ore body appears to be a variety of Skarn, 
due to the abundance of Albite admixed with Quartz, which is the white material holding the Sulfides.

The sulfides appear to be a mix of Iron Pyrite, and Possibly Arseno-Pyrite.

The Wall Rock enclosing the outcrop of the Ore Vein is a variety of Rhyolite.

Rhyolite can, and does differentiate directly from Granite, and rock-types with a "Skarn-Type" chemistry/composition can occur by the agglomeration of Quartz and Feldspar's within a molten magma of Granitic /Rhyolitic composition. The Feldspar's get decomposed into Kaolin by Hydrothermal Solutions, which creates a naturally occurring filter for all hydrothermal solutions flowing through it, thus creating the High-Grade sulfide loaded zone that you found. 

I'm pretty sure that's emplacement process in this instance due to the fact that there isn't a sharp change from the chemistry of the vein to that of the surrounding rock, as there would be with an intrusion such as that of a Dike or a Sill.

That ore does look promising. 
Let us know what the assay results are when you get them.
A few more photo's would be nice, if you have them.

I hope that this has been helpful and informative.

Sincerely, Rick. "The Rock Man".


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## Militoy (Jun 11, 2011)

Richard36 said:


> ...due to the abundance of Albite admixed with Quartz, which is the white material holding the Sulfides....
> 
> Sincerely, Rick. "The Rock Man".



I'm curious as to how you determined the presence of albite? I didn't spot any twinning in the ore photos - and of course it's not possible to get a streak or speG test from a photo. Were you able to make the identification solely based on the appearance of the photos - or by some clue in the descriptions? Thanks for sharing your experience!


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## Richard36 (Jun 11, 2011)

Militoy said:


> Richard36 said:
> 
> 
> > ...due to the abundance of Albite admixed with Quartz, which is the white material holding the Sulfides....
> ...



If I remember correctly, Albite is a Feldspar, but regardless of whether or not Albite is, or isn't a Feldspar, 
Kaolin is produced from the decomposition of Feldspars by Hydrothermal Solutions. 

The two close-up photo's clearly show Kaolin with Sulfides within it. 
So whether or not twinning of any mineral can, or cannot be found, 
Feldspar of some sort had to be present for the Kaolin to have formed.

Massive Albite looks a whole lot like Milky Quartz, or "Bull Quartz" as it's called by some.
Albite with Quartz is more translucent than Milky Quartz, and often weathers to a slick finish on the exposed surface.

I hope that this helps.

Sincerely, Rick. "The Rock Man".


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## Palladium (Jun 11, 2011)

I don't know if you have been thanked lately Rick, but if you haven't just let me be the first to thank you. I only wish i could understand half of what you just said.


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## Militoy (Jun 11, 2011)

Richard36 said:


> ...If I remember correctly, Albite is a Feldspar, but regardless of whether or not Albite is, or isn't a Feldspar,
> Kaolin is produced from the decomposition of Feldspars by Hydrothermal Solutions.
> 
> The two close-up photo's clearly show Kaolin with Sulfides within it.
> ... "The Rock Man".



OK - I believe I'm starting to follow the logic. You have identified the presence of kaolinite clay in the photo; so there must have been some kind of aluminous silicate (like feldspar) to provide the source of the material.

Can you share some of the clues you used to identify the matrix as kaolin-based? I vaguely recollect using x-ray diffraction to ID kaolinite when I was in school - but that was a long time ago - and I don't recall what other indications one might use to make the identification. Thanks again for taking the time to share your knowledge!


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## Richard36 (Jun 12, 2011)

Experience from looking at many outcrops up close and in person is all.
I'm pretty sure that's Kaolin. If so, the following should apply.

The white material should be soft, 
to the point of being powdery, unless bound up with a small percentage of quartz,or Silica. 
but will still powder with relative ease by trying to cut, or crush it.

Similar in texture to Borax that has absorbed moisture from the atmosphere, 
then evaporated, thus forming a solidified chunk of material. Kaolin will do the same thing.

Kaolin will turn into a malleable mass when wet, 
and often will turn into a mud if soaked in water for a day or two.

Kaolin almost always has a dull Earthy luster as well.

I hope this helps.

Sincerely, Rick. "The Rock Man".


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## Richard36 (Jun 12, 2011)

Palladium said:


> I don't know if you have been thanked lately Rick, but if you haven't just let me be the first to thank you. I only wish i could understand half of what you just said.



Thanks Palladium. 8) 

I appreciate it. For real.
What part of what I posted did you not understand?

Anyway, here's a photo of Quartz that looks like it has some percentage of dissolved Albite within it.
There is the possibility that I may be mistaking a Pyroxene, or Amphibole mineral within this piece of Quartz as Albite.

The milky translucent nature of the stone, combined with the way it weathered to a slick finish is the "Give-Away" identifying features that I look for when deciding if some chunk of Quartz contains any percentage of Albite or not.




To me, Albite is a good thing. 
It forms within various Hydrothermal Vein systems, 
Alpine Vein Systems for certain, and forms within those in abundance.

That fact is why it is regarded by me as a primary indicator of being within a correct region to find decent vein systems.

I hope that this has been helpful.

Sincerely, Rick. "The Rock Man".


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## demons26 (Jun 12, 2011)

so have you crushed the albite I gave you yet LOL. and if you have where's my gold j/k LOL


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## Militoy (Jun 12, 2011)

Richard36 said:


> Experience from looking at many outcrops up close and in person is all.
> I'm pretty sure that's Kaolin. If so, the following should apply.
> 
> The white material should be soft,
> ...



Thanks for explaining that. Since rhyolite is a felsic mineral with low iron and magnesium, do you believe the iron pyrite (and iron oxide) actually came from the rhyolite, or from some later intrusion (or was it already there when the rhyolite was extruded)?


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## dtectr (Jun 12, 2011)

Magmatic waters that percolated thru fractures & voids during & following intrusion?


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## Richard36 (Jun 13, 2011)

dtectr said:


> Magmatic waters that percolated thru fractures & voids during & following intrusion?



Yup. That's what I would think.
Excellent guess.


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## Hephaestus (Jun 27, 2011)

First of all thanks for the knowledge Rock Man. I'm slowly reading some threads about ores and notice the full of knowledge posts you make. Thank you in advance.

As I'm new in the ore prospecting, I have a basic question regarding the yellow areas of the ores Steve -sfuller5- shows. Is that where gold might be? Or is it in the brownish areas?


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## Richard36 (Jun 27, 2011)

Hello Hephaestus,

Thanks for the compliments, I appreciate it.
As for your question, the yellow and orange areas, as well as the shinny metallic material are what to be looking for. 
The yellow and orange areas are the indicator stains, the metallic sulfides are the actual Ore Minerals containing values.

I hope that this helps.

Sincerely, Rick. "The Rock Man".


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## Hephaestus (Jun 28, 2011)

So, as I read on other threads, these yellow and orange areas are oxidized sulfides with brown being pyrite? Also, these shiny metallic sulfides have Si in them? That's why they shine?


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## Richard36 (Jun 28, 2011)

Hephaestus said:


> So, as I read on other threads, these yellow and orange areas are oxidized sulfides with brown being pyrite? Also, these shiny metallic sulfides have Si in them? That's why they shine?



Yes, the brown and orange areas are the oxidized sulfides.
The sulfides are shiny because they are a metallic compound.
Si is silica, and sulfides do not contain silica.


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