Prospecting--Part 2 What Minerals are in the Area?

[chrisski]

Finding Open Ground to Prospect, Claim or Metal Detect

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Part 2 – What Minerals are in the Area?

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I. State Publications

II. USGS Maps

III. USGS Surverys

IV. MineDat.org

V. MRDS (Mineral Resource Data System)

VI. My Land Matters

 

This section talks about my technique for finding what type of minerals are in the area.  With this section, still not at the point to where I have decided the exact place I put in my GPS that I will be swinging the metal detector, but this saves me some heartache about going to a non-gold bearing area to detect gold nuggets. 

Part 1 talked about checking land status which is finding land could be eligible, but not at the level of detail about staking a claim.  You could of course use this section first and then once you find a gold bearing area, start the land status study. 

With the name of a mine, internet searches will turn up anything from hundreds of pages of useful information to none at all.

 

I. State Publications

The state I live in, Arizona, has many publications available for download, a common one referenced is Placer Gold Deposits of Arizona.  The history of each county from Arizona is discussed, and this is the index for Maricopa County:

There’s six pages of information from the county and each district containing an introduction which includes the general location and maps:

“9. SAN DOMINGO DISTRICT

Location: South flank of the Wickenburg Mountains, northeast of the Hassayampa River, 7 N 4 W.

Topographic maps: Wickeburg and Red Picacho 7 ½ minute quadrangles.

Geologic map: Wilson, ore, and :feirce, 1957, Geologic map of Maricopa County, scale 1:1375,000.”

 

And other good info spread throughout the 3 pages like “The origin of the placer gold is said to be from Precambrian and post-Cambrian veins in the area,” which could lead you to an idea to search for older pre-Cambrian rock on a geological map.

Also listed are 10 references which if found will give more info in the district.

II. USGS Maps

I have found USGS maps to contain info on mining that can be used for research.  These are available for free download at The Map Locator on the USGS store. Need to be able to read the maps and the USGS Topographical Map Symbols is extremely helpful, especially the mining symbols:

This is an example of a USGS map of an area I went which show several mine shafts and prospects, and an example of the tunnel I found when I went out there:

 

I will point out I do not enter the mine shafts, even when noone is looking.  I’m not just saying that for liability. I don’t enter, but I do look at the tailings on the outside of the tunnels.

Even though this is a gold bearing area, when I found this copper ore, likely was not a gold mine, but an older copper mine:

III. USGS Surverys

Another good reference is Geological Surverys.  A USGS survey of some sort exists for your local area.  Some of these documents can be in excess of 100 years old.

One that was recommended to me in this post for Arizona and the Bradshaw Mountains is the “Geological Map of the Bradshaw Mountains Quadrangle, Arizona” Surveryed in 1901 and published in 1926 along with the "ORE DEPOSITS OF THE JEROME AND BRADSHAW MOUNTAINS QUADRANGLES, ARIZONA" published in 1926. 

The tip from @desertpilot is:

“So the key to Bradshaw gold is the Yavapai schist belt. If you look at the linked map you can see a horseshoe shaped deposit that spreads across the Bradshaws. Now if you cross check that with a topo map or AZGS AZ mines .kml you will see that most of the gold mines are in or on the edge of the belt. The veins are of pre-Cambrian age. The linked USGS Bulletin 782 is a good starting point. If you’re in the schist belt and see quartz stringers especially with malachite or azurite associated I'd slow down and focus on that stuff.”

Azurite (blue) and Malachite (Green):

The Map:

And how the Yavapai Schist is indicated:

And the report:

IV. MineDat.org

Many internet searches lead back to Minedat.org.  This is some info it has for the Vulture Mining District around Wickenburg. 

And this is the Lead Dike Mine in the Vulture Mine District which shows it mines Ag (Silver) –Zn (Zinc) –Pb (Lead) –Cu (Copper) –Au (Gold) -V (Vanadium) mine.  Although gold is listed as a mineral produced, not only was it last in the list, this was a hard rock mine and an indicator of gold in the area, but not in placer quantities.  So, perhaps some ore is in the tailing piles, but these would have to be open and not claimed to search.  My metal detecting in tailings piles has turned up much iron junk and no precious metals.

 

More promising would be a placer if that could be located.

I have not found the Geographic coordinates listed on the minedat webpage to be good enough to be entered in directly to a GPS, perhaps a mile or so.  A bit more looking will need to be done.  I do find the symbols off the USGS 1:25,000 7.5 minute quadrangle maps get me within a 100 feet.

 

V. MRDS (Mineral Resource Data System)

 

The MRDS is government website listing production and other mineral data.  This is an example of info that appears when the different layers are checked off:

Clicking on a site will bring a list of that site:

Clicking on the Deposit ID number by the mine name will produce a nit of info including list of minerals:

I have not found the Geographic coordinates lited on the MRDS webpage to be good enough to be entered in directly to a GPS, perhaps a mile or so.  A bit more looking will need to be done.  I do find the symbols off the USGS 1:25,000 7.5 minute quadrangle maps get me within a 100 feet.

VI. Mylandmatters.org

Of course my land matters will contain a lot of info on an area. I go to the mining claims maps and turn on top minerals, mineral patents, and MRDS Mines

Clicking on the audit next to the dry river brings up information.  A bit more research is needed to find out about the comeback claim that produced lead and copper or any other information.

 

End of Entry

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If picture appears below, disregard

 

Edited October 1, 2022 by chrisski
Got rid of duplicate picture at end

[sleepyjim]

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