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Lady
09-26-2012, 09:57 PM
Gossan

(iron hat), a residual formation that occurs in the surface parts of ore (primary sulfide) deposits of copper, lead, zinc, and other metals as a result of chemical weathering and oxidation of the primary minerals of the ore body. Gossans consist primarily of iron oxides and hydrous iron oxides (goethite, hydrogoethite, hydrohematite, turgite), and as a result they are usually dark or light red, ocherous, or brownish red in color. The formation of gossans is associated with the oxidizing action of surface waters and is accompanied by the secondary enrichment of ore deposits. In the process of weathering, the sulfides of copper, silver, zinc, and other metals oxidize to easily soluble sulfates, after which they are leached and carried to deeper parts of the ore body. At the same time the iron in sulfurous compounds—pyrite, chalcopyrite, and other sulfides—is only partially removed in the form of a soluble salt (sulfate of iron oxide); most of the iron is oxidized and hydrated and remains in place in the form of hydrates of iron oxide (brown iron ores). These secondary brown iron ores, occurring as a result of the transformation of original pyritic and other ores containing iron sulfides, are what form the gossans near the earth’s surface. The depth at which gossans are found beneath the earth’s surface is usually restricted to the groundwater level and may extend to dozens or even hundreds of meters. In comparison with initial sulfide ores gossans are richer in iron in their upper parts and in gold in their lower parts. Contrasting strongly with the enclosing rocks, gossans serve as an important indicator in explorations for sulfide-ore deposits and in identifying the primary ores concealed in the depths.

And it says, (gold in the lower parts). We found gold in our moss sample and continue with each stage of sampling. ? What do you think?

geowizard
09-27-2012, 07:01 AM
Michelle,

This is a good sign.

Many if not most mines begin with a gossan. Early explorers used their eyes primarilly for the purpose of looking for gossans. The size of the gossan can also indicate the scale of mineralization. The more exploration you do that opens the surface and exposes the gossan, the larger the deposit contained beneath. That isn't to say the gold producing zone is particularly larger. The panning and other assay work will define how large the deposit is.

Depending on your ambitions for your new discovery, it may be worth while to contact an exploration company. The usual scenario is that they will spend their time and money to drill and sample further at depth. They will pay you a negotiatied sum of money at signing of an exploration lease, make all of the annual rent payments, complete the required affidavits of labor, document the data obtained and if you ask for copies of the data, you will be copied. The exploration company will also pay you an annual lease payment per your negotiation. The exploration company will have the option to buy the claims at their discretion. A wise mining claimant having a lease will also have included in the lease that you retain a production royalty on all of the gold that is produced. The next step is proprietary and if you will send a PM, I will give you advice.

- Geowizard

Bill Bohan
09-28-2012, 02:34 PM
I would assume that by the exposure of some of your vein discoveries, that your near surface veining would be signatured by gossan at the surface even to the point of over lapping the vein. As you go further down , the crumble portion of the vein will become more resilent and less exposed to atmospheric conditions of ice , air , ice, oxidation , and more ice and water. Your gossan signatures at grubstake should be more linear but with diminished rust at depth

Bill Bohan
09-30-2012, 10:57 AM
While at the underground gold mine Pogo here in Alaska. I was able to view closely several elevations and headings of the Leise vein . I noticed that beneath the water table there was signifigantly less rust along an in the main quartz vein. Above the water table and near the surface portions of the vein, rust was more prevalent within in and around the heading.
I could be wrong but I don't recall the Pogo vein quartz being exposed at the surface, but I do know that the mineralzed assayed signature was exposed at the surface.

Bill Bohan
09-30-2012, 11:05 AM
Color schemes in gossan and laterite soils are mostly made up of the three minerals: limonite, goethite and hematite plus clays and clay types.
Perhaps (not sure) your yellow zone is a limonite mixed with Ate-sulfer and clay while your maroonish zone is a hematite mixed with Ide-sulfer and clay.

geowizard
09-30-2012, 11:53 AM
Michele,

A must read is "Models and Exploration Methods for Major Gold Deposit Types", Paper 48, by Robert, Brommecker et al.

You have gold.

The next thing to learn is the "deposit model". The deposit model can be identified through multi-element assay for Bismuth, Telurium, and Arsenic. Each of these elements establish a "metal signature".

Examples:

Greenstone hosted deposits Au > Ag, As, W signature

Turbidite hosted veins Au > Ag, As Signature

BIF hosted Au > Ag, As signature

Intrusion hosted Mesozonal Au > Ag, Bi, As, W, Mo Signature

Sediment hosted Intrusion Related Au > Ag, Bi, W, Mo Signature

etc... etc...


- Geowizard

overtheedge
09-30-2012, 04:03 PM
Thanks for the reference geowizard. I found it with just the title and downloaded it.
eric

geowizard
09-30-2012, 05:23 PM
Thanks, ote,

A second paper that zero's in on Alaska is: "Exploration Models for Mid and Late Cretaceous Intrusion-Related Gold Deposits in Alaska and the Yukon Territory, Canada" By Brian Flannagan, Curt Freeman, Rainer Newberry, Dan McCoy, Craig Hart. This paper, because time is relevant, adds the period of mineralization into the equation and references "proximal, distal and shallow,deep" as take-aways. This paper is over the top!

I keep these two papers within reach at all times and recommend them both.

- Geowizard

Lady
10-05-2012, 08:35 PM
Thank you Bill and Geo, really interesting information. One is that the visiting Geologist from the Colorado School of mines showed us the wall rock and it is near an out cropping. I have to say its all very hard to understand. Once we have our assays will have some ideas. The paper by Robert Brommecker was very informative. Most of the out crops we have discovered has been red dirt, our Blueberry is the first showing of yellow. We wont know what it is until the assay's come back.

chickenminer
10-06-2012, 03:10 PM
A second paper that zero's in on Alaska is: "Exploration Models for Mid and Late Cretaceous Intrusion-Related Gold Deposits in Alaska and the Yukon Territory, Canada" By Brian Flannagan, Curt Freeman, Rainer Newberry, Dan McCoy, Craig Hart. - Geowizard

Wiz...
THANKS for pointing out this paper. What a great read!

geowizard
10-06-2012, 06:37 PM
Dick,

You are welcome! I hope it helps you figure things out on your mine. We're surrounded by clues. The hard part is figuring out what a clue looks like! :)

- Geowizard