Ever see mineralization like this while hunting gold? New to me.

[Boarteats]

Apologies in advance for the “what is this” question. I’ve gotten pretty good at identifying rocks and minerals in my area, but I’ve not seen this before. Any thought on what the dark mineralized areas are. My best guess was a telluride. I believe that the host rocks are feldspar.

I’ve started to find mineralization like this in an area where I’ve found a pretty good amount of silver (in the form of silver chloride) and am starting to find some really fine gold (only a very small amount so far). Gold is getting better as I dig down. These rocks came from a layer of very densely packed gravel and rock a few feet below stream bed (not hard pack). I originally believed that these rocks simply had been covered with manganese dioxide. However, breaking some of them revealed that the mineralization is inside as well, quite a lot of it.

 

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[hunterbill]

Are they magnetic?

 

[smokeythecat]

Looks like iron residue, the stuff black sands is made from. It's always good to find the black sands.

 

[Boarteats]

Are they magnetic?

Not attracted to magnet at all. I tested with a really strong neodymium magnet. Also, propane torch doesn’t affect it. Neither does HCL.

 

[Boarteats]

Looks like iron residue, the stuff black sands is made from. It's always good to find the black sands.

Lots of iron oxides in this stream. I've collected a small bucket of magnetite along with other dark heavies left over after panning. The reddish brown portion could have an iron oxide component ..if not entirely iron oxide. However, the dark grey material doesn't look like iron oxides to me. Admittedly, prospecting is a hobby, so my experiences are minimal.

 

[Bejay]

Not enough mineralization to give a thought to. Near as I can tell the samples are stained.

Bejay

 

[Gambrinus]

That might be porphyry.

https://en.wikipedia.org/wiki/Porphyry_(geology)

 

[Goldwasher]

looks like common staining from exposure.

The mineralization of loose rock and cobble will tell you very little.

You need to find mineralization in the country rock. Concentrations of it. You have to consider the whole of the earths crust is mineralized..Your looking for the sweet spots.

 

[Goldwasher]

That might be porphyry.

https://en.wikipedia.org/wiki/Porphyry_(geology)

I don't see enough of the rocks grain to make that ID .

 

[Terry Soloman]

Here is some gold ore:

 

[Boarteats]

Here is some gold ore:

What is your host rock, feldspar, quartz, calcite? Most of the rocks that I’m finding look very similar. Should be easy enough to crush my rocks and pan, I suppose. I additionally have silica rocks (maybe quartzite) that have a crazy amount of iron staining. Also, has various sulfides, purple/blackish. These, are too hard for me to crush. However, great for polishing with an angle grinder

 

[Boarteats]

That might be porphyry.

https://en.wikipedia.org/wiki/Porphyry_(geology)

Interesting comment. The Baltimore Gabbro Complexe is a large itrusive igneous rock formation that underlies the area where my streams are located. However, the rocks don't look porphyritic in person.

 

[Boarteats]

looks like common staining from exposure.

The mineralization of loose rock and cobble will tell you very little.

You need to find mineralization in the country rock. Concentrations of it. You have to consider the whole of the earths crust is mineralized..Your looking for the sweet spots.

This info helps a lot! Sounds like all one can do with alluvial deposits is look for concentrations of heavy minerals such as iron, since that will be where gold will tend to settle. Specific rock composition isn't terribly informative since alluvial deposits are a hodgepodge of rocks that came from somewhere else.

I know someone nearby who has what appears to be an extremely weathered outcrop of dark rock on their property. Also, has white quartz in ground but I don't know if I am seeing large chunks of quartz that came from elsewhere or if the quartz is part of a larger body of buried rock. Might be time to make a new friend.