# Hephaestus' prospecting



## Hephaestus (Jun 28, 2011)

So after some quick questions for the Rock Man I now have my own thread to ask more formal ones. 

For scale, in the last photo, top left specimen is 4,5 cm in widest point, top right is 2,5 cm in widest point.

Could they have some kind of sulfides?

There was also some quartz (I think) which was surrounded by that type of rock. Some specimens I got were turning from white to yellow/orange.


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## Reno Chris (Jun 29, 2011)

The orange/rust coloration is likely the result of oxidation of sulfides in the ore (or may have been in the ore). 

Chris


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## Richard36 (Jun 29, 2011)

Reno Chris said:


> The orange/rust coloration is likely the result of oxidation of sulfides in the ore (or may have been in the ore).
> 
> Chris



Yup. 

The photos don't have much for details, so that's as much as I would have been able to tell ya.
The bulk of the rock is Quartz, as you suspected. The white patches are probably Albite, or Kaolin.
Sorry I couldn't be of more help, lack of telling details in the photos.

Sincerely, Rick. "The Rock Man".


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## Hephaestus (Jun 30, 2011)

Thought so. Not to worry. I have more.  Thank you both.

As I said there was some quartz turning yellow to orange with the last picture showing some rather interesting stuff. Shines from every angle.


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## Reno Chris (Jul 1, 2011)

The shiny stuff is mica - it has no particular value. The enclosing rock is probably a mica schist. The white stuff appears to be quartz, but without an assay, there is no way to know if it contains any values or not. 

There are many, many quartz veins, but only some contain gold, silver or other values. Quartz is made of the two most common elements in the earth's crust - silicon and oxygen - that's a big part of why its so common.


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## dtectr (Jul 1, 2011)

Would it be possible for you to post a photo of a the deposit, as in the first photo, but with more of the surrounding "soil"? 

It is difficult to tell if the quartz body is intrusive, as in remnants of a dike. Or if it is still present after the surrounding material kaolinized.

Also a close-up photo of the surrounding "soil" or rock, where the little quartz stringers appear, to the left of the deposit, in your first photo.


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## Hephaestus (Jul 1, 2011)

Thank you Reno Chris. I'm trying to learn how to distinguish between "good" and "bad" quartz veins. The color variation and that this vein is surrounded by this kind of dirt, got my attention.



dtectr said:


> Also a close-up photo of the surrounding "soil" or rock, where the little quartz stringers appear, to the left of the deposit, in your first photo.


You mean those far left on that photo?

I have a photo of the surrounding but it's not so good. I have to take another one after I cut some of the trees' branches. Quartz is somewhere on the lower right or outside the photo -can't be sure.


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## Reno Chris (Jul 2, 2011)

*



trying to learn how to distinguish between "good" and "bad" quartz veins

Click to expand...

*
The good ones have gold. The bad ones have little or no gold. Simple as that. 

You cannot however just eyeball a vein and tell if its good or not, unless it has lots of visible gold. Lots of pretty good veins have little or no visible gold however.

One simple test is to collect a few kilos of the vein material, crush it to powder and process the crushed material with a gold pan. If it has significant free gold mixed into the quartz, you will see it at the bottom of the pan.

Chris


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## Oz (Jul 2, 2011)

Reno Chris said:


> One simple test is to collect a few kilos of the vein material, crush it to powder and process the crushed material with a gold pan. If it has significant free gold mixed into the quartz, you will see it at the bottom of the pan.


But you can also have a good vein of refractory material or sulfides, and nothing will show in the pan.


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## Reno Chris (Jul 2, 2011)

> *But you can also have a good vein of refractory material or sulfides, and nothing will show in the pan.*



Very true. That is also why the Carlin deposits of Nevada, with hundreds of millions of ounces of gold, were not discovered until the 1960s - their gold is microscopic - too small to pan out. The only way to know for sure is to do an assay. However, most gold bearing quartz veins have at least some free gold, so it is a fairly reliable rough and dirty type of test.


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## Richard36 (Jul 2, 2011)

Reno Chris said:


> [ most gold bearing quartz veins have at least some free gold, so it is a fairly reliable rough and dirty type of test.



I've found this not to be true, as most Quartz Veins that contained native gold have long since been found, and pretty much mined out, with a few exceptions. What seems to be left for Gold Bearing veins are those with micron gold bound up within Sulfides, or as surface coatings on Oxides such as Black Sands in placer deposits.


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## dtectr (Jul 2, 2011)

Hephaestus said:


> Thank you Reno Chris. I'm trying to learn how to distinguish between "good" and "bad" quartz veins. The color variation and that this vein is surrounded by this kind of dirt, got my attention.
> 
> 
> 
> ...


Rick
Is that metamorphosed sedimentary rock, decomposing? Whatever it WAS, it seems to have been altered by heat & pressure.
I was thinking sedimentary, because of the cobble in center left & the banding still visible to the center right with the tree branch shadow over it? 
If so, would the large quartz mass more likely be "leftover" from the original rock layers with the smaller quartz (or feldspar?) stringers be from the later action? If so, I was thinking that 

I've been in the heat & humidity all afternoon & my brain just quit working ...
sorry
EDIT: Clarity & correction


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## Richard36 (Jul 2, 2011)

It doesn't quite fit the description of a sedimentary rock, but I do see what you mean, and why you think that. I see what you are looking at. I can't enlarge the photo enough to see the details I need to see in order to say for sure that was created by chemical sedimentary processes, but yes, that is a possibility.

As for the heat, It's in the 80's outside here, and I've been out in it for the last three hours prospecting yard-sales.
Some gold plated jewelry, and a few gold plated nicknacks, ceramic salt and pepper shakers mostly.


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## DarkspARCS (Oct 19, 2011)

Hephaestus...

Your best bet in locating a gold rich deposit is by doing the research on the geologic history of the area you're interested in. Your state university or dept. of mining/ geology will have geologic reports, terrain drainage maps, even sample assay reports - from geologists who received state funding for their field studies that generate such reports.

These reports usually can be found either on the state's mining/ geology website, or in the state university's library. Of interest, are locations described as either having been subjected to a meteor impact, or have historic volcanic activity that has since become inactive. What you're looking for are descriptive terms such as "*PolyMetallic Replacement Deposites*, or *Impact Fracturing*.

If you locate areas with formations described with these terms, go physically inspect them, using the report maps to find specific rock formations... usually black or red in appearance, and hard as quartz, perhaps even embedded with various ferrous and/ or non ferrous metallic crystals (ferrous = pyrite or hematite, non ferrous = arsenopyrite, chalcopyrite, galena, sphalerite), and possessing tell tale oxide stains (green, blue, azure, red, black, or orange surface pigmentation). 

If it is described as an impact formation, look for deeply colored formations of reddish to black material that is dense and heavy. Smell the rock - does it smell like metal? If so, that's because it is, and not only that, a high grade metallic ore as well, since it was subjected to intense heat and pressure that has purified the deposit to a higher elemental grade.

Don't forget, Iron is one of the best precipitators of gold, as too, mercury the amalgamator of gold. Both metals possess ores of a deep reddish black material. Where these ores are located too, you will find them possessing a percentage of gold.


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