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For those curious, I flew my drone over the Gold Hill Pocket gold mine in Oregon and filmed it. The same we are discussing in this thread: 

 

 

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Great Topic! Thanks for bringing it up :biggrin:

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WOW....awesome footage. Thanks for the effort & putting up for us to see. Top marks. Go to the front of the class. :biggrin:

Good luck out there

JW :smile:

 

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The original links are apparently no longer active.  

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I am apparently a little more than confused. When you say "pocket gold" are you including pocket mining? 

In1999 the Tuolumne County Historical Society republished a 1901 edition of the illustrated  historical brochure of "Tuolumne County California" which covered the patent mines and mineral belts through the county.  The brochure has a section on "pocket mining" in the vicinity of Bald Mountain and the Big Bonanza pocket mine. It defines "pockets to mean an agglomeration of gold held by quartz and often solid masses of metal without any quartz. From the text  " Pocket mining is reduced today (1901) to an absolute science... Understanding this class of mining watch for every sign known to the practical miner....Shoots almost invariably come to the surface and continue down on the line of crossing till a pocket is found. There are other things needed besides crossings- the right kind of metallic slate, that cuts the veins obliquely; then there are gold seams, which are small quartz feeders, that the strike into the vein at certain angles. Often they of themselves are rich in gold...

Here is what I gather: a main fissure vein strike is some where around 30 degrees west of north with metallic slates on both the hanging and foot walls. At varying depths where the shoots (quartz stringers?) cross the main fissure vein at an oblique angle gold seams (pockets) can form. Am I correct?

Is this related in anyway to the Gold Hill pocket deposits?

 

 

 

 

 

 

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According to a couple of diagrams of the Bald Mtn pocket deposits. A diorite dyke fissure containing three quartz veins has a  strike of N 30 W cutting across a slate formation with a strike of N 30 E. The dip of the dyke is 30 degrees west with one quartz vein at the hanging wall, one at the foot wall and one middle vein. The multiple gold seams are indicated where narrower quartz feeders that strike the main diorite dyke veins at an angle. Apparently, it was not uncommon for one the dyke veins to be barren at the feeder seams.

The top view diagram indicate four crossings lines running parallel within & along the strike of the diorite dyke. Where these crossings intersect the gold seams of the quartz feeders gold pockets form in one or more of the three dyke quartz veins. 

I am not clear on what the crossings lines are indicating. Where the dyke veins cross the feeder seams? There are several references to shoots which I assume is referring to the combination of diorite dyke vein structure.

 

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Great thread.

Yesterday and today I and about 40 other people, of all flavors, attended a metal detecting outing for hillside pocket/placer gold on a side hill side above the Klamath River just downstream of Happy Camp, Ca. 

The outing was a combined effort of Whites Electronics (metal detectors), Armadillo Mining Supply, Tom and Josh Bohmker, and The New49ers, on whose claim we were detecting. Although rainy, it was good fun and great lessons in metal detecting for gold.

All who put this outing on are very good at what they do. As the topic of this thread is pocket gold hunting, I'd like to give a big shout out to Tom Bohmker and his son Josh as truly knowledgeable people on pocket gold and finding it. It was a pleasure to meet and learn from them. Tom does have quite a few good publications on the subject.

All I found was a lot of old square nails.

Mike

 

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"Fists Full of Gold" by Chris Ralph has a good section on "seam deposits" that appears to be related to "pocket deposits" and quartz feeders.

Diorite is a member of the diorite/gabbro family which are a meta-volcanic. Greenstone meta-volcanics are a source for chloride.  I found a old reference to the "crossings" as being partially open and as running within and parallel with the diorite dyke's strike. These crossings are also composed of diorite. The "crossings" refer to the crossing with groups of quartz feeders within the diorite dyke to form pocket gold. The requirement for a metallic slate may be referencing to the requirement iron sulfides.

According to Chris gold may be deposited in three hydrothermal mineral pulses. After the main fissure is full the third pulse fills the seams (feeders?) without closing off the seams completely. This may be how the quartz feeders continue to fill the "pockets" within the diorite dykes.  

I have been working a claim know for pocket gold with the following sequence from west to east: black slates with iron sulfides and narrow quartz stringer, greenstone of either dibase or grabbro with narrow quartz stringers, serpentine, the main fissure quartz lode vein then a igneous feldspar porphyry. Old surface diggings follow the surface stringers to the crossing with the main quartz vein with deeper excavations at these intersections. What gold I have found is rough but not as rough as you would expect from a pocket deposit. 

Merton found a reference to "potash feldspar" in the study of the Shoo Fly Complex.

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"Orogenic Gold Deposits" by geology films 2014 (on YouTube) covers mountain building, high pressure fluids, faults, earthquakes, pulses and gold deposition.

One item of interest was regarding the precipitation of gold after crossing a wall rock containing "carbon". The carbon (C) combined with hydrogen (H) to form methane (CH4). Methane (gas) interacted with the quartz solution causing the gold to drop out of solution is the green schist zone.

The Tuolumne County pocket mines were associated with "diorite dikes" and secondary quartz crossings passed through a "black mineralized slate" wall rock. These crossings were at an acute angle to the the primary NW vein (Sonora Fault). 

The Siskiyou pocket mines are apparently associated with "Andesite" dikes which is the extrusive equalivalent of the intrusive "Diorite".

There are seven short informative videos covering the Orogenic deposits around the Pacific Rim, check them out. 

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  • Similar Content

    • By Steve Herschbach
      Another question via email, with personal references removed. I prefer to answer these on the forum so everyone gets the benefit of the answer plus others can offer their opinions also.
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      The text mentions that placer deposits were discovered at Elizabethtown in Colfax County, and the map shows that as the Elizabethtown-Baldy mining district. Following along in the text we find this:
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      Lindgren, Waldemar, Graton, L. C., and Gordon, C. H., 1910, The ore deposits of New Mexico: U.S. Geol. Survey Prof. Paper 68, 361 p.
      Henderson, C. W., 1932, Gold, silver, copper, lead, and zinc in New Mexico: U.S. Bur. Mines, Mineral Resources U.S., 1929, pt. 1, p. 729-759.
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