Macros for TomH

[Nugget Shooter 4,617]

Tom asked for some close shots of the Magnetite/Gold specimen from last week so here ya go...

[Knifemaker84 257]

Amazing!!!

[Sonoran Dave 2,146]

It's cool how well it sticks to a magnet! Bill got a little green around the gills when I turned his pick upside down to show my girlfriend the magnetic nugget. 

 

[TomH 2,849]

Very cool! Thanks. I like seeing the detail of nuggets.
Tom H.

 

[nugget108 1,743]

That is a cool nugget Bill. The way the 2 colors go together looks great.

[Bedrock Bob 4,057]

There is a hill called Volcan in the Hillsboro District where the gold looks just like that. In the rest of the district the waste rock in the placer gold is usually associated with pyrite pseudomorphs and occasionally rusty quartz. In this particular area the gold is wrapped up with magnetite. 

I was told by an experienced miner in the area that all the hard rock veins in the district went to magnetite at depth. Volcan lifted the deep veins to the surface and resulted in the magnetite placer gold. The rest of the placer gold in the area was derived from oxidized sulphide ores and cemented fossil placer that originated from much closer to the surface.

Back in the early 80's a couple of fellows had a fairly sizeable placer operation in that gulch. There were lots of "dirty nuggets" wrapped up with magnetite. On the end of the elevator that served the trommel there was a big drum magnet to pull out black sand. Once in a while you could find a nice little chunk in the pile of black sand that got pulled under the elevator belt. 

After they pulled up stakes we found a lot of gold cleaning up around the old wash plant and concentrates building. Much of it was wrapped up in a magnetite matrix. And wherever there was a pile of black sand they removed with magnet we found them.

Most platinum nuggets stick to a magnet too. 

[homefire 2,581]

And hence to old timers saying "" Gold Rides a Iron Horse ""    Gold has more then some affinity with Iron.

[Sonoran Dave 2,146]

6 hours ago, homefire said:

And hence to old timers saying "" Gold Rides a Iron Horse ""    Gold has more then some affinity with Iron.

There has always been iron in some form present in every instance I have found gold in hardrock here. Found a lot of iron with no gold though. 

 

 

[Rob Allison 63]

Hey Bill,

   What are you you using for the Macro shot?  A digital camera with Macro or something like a microscope?  Great picture and specimen.  

Thanks for sharing. 

P.S.  A friend of mine stopped using a "super magnet" for this very reason.  He found a small iron/gold specimen on the magnet while he was cleaning it off.  He said he believes he could have tossed many over the course of years of nuggetshooting.  Makes me wonder how many I could have tossed, I always use a very powerful Neo-Nym Super Magnet ..... 

Rob Allison

Edited January 18, 2019 by Rob Allison

[Bedrock Bob 4,057]

From my experience hematite is where the gold begins and magnetite is where it ends. Iron on both ends of the equation. Hematite near the surface above the supergene enrichment in oxidized ore and magnetite at depth below the copper sulphide. The iron that is actually associated with the gold is generally iron pseudomorph after copper sulphides though. So while iron is a really important constituent of a gold vein it is the presence of oxidized copper sulphides that are the key. I have always said while iron is important it is the copper and oxidization that makes for a good placer.

Almost every substantial chunk of gold I have ever found near hardrock veins has had ilmenite cubes after copper sulphides in it. Much more so than quartz or any other gangue material. That may be unique to the areas that I am familiar with but it is definitely a pattern in my haunts.

The richest placer I have ever worked has absolutely no gangue material in it. You will NEVER see waste rock in the gold and there are no hardrock veins. It is placer only and only in reworked gravel. Any host veins have weathered away thousands of years ago. But while there are virtually no gold veins left in the mountain a heavy ironstone layer marks the spot where they once originated from. 

 

[Sonoran Dave 2,146]

Bob your area sounds a lot like ours here in central AZ. If I see copper signs,I slow down and look very carefully. Back in my old hunting area in Alaska...no copper whatsoever. It just depends on the composition of the molten stew below. 

[Bedrock Bob 4,057]

38 minutes ago, ArcticDave said:

Bob your area sounds a lot like ours here in central AZ. If I see copper signs,I slow down and look very carefully. Back in my old hunting area in Alaska...no copper whatsoever. It just depends on the composition of the molten stew below. 

Mmmmm… Molten stew. I like mine tangy with just enough sulphuric acid to get some electrolysis going. Served with a big helping of frost heave and a side of deflation. What a lunch!

Edited January 18, 2019 by Bedrock Bob
...Almost forgot the tortillas. Gotta have those.

[Morlock 1,722]

17 hours ago, Nugget Shooter said:

Tom asked for some close shots of the Magnetite/Gold specimen from last week so here ya go...

 

I.just love the gold in magnetite contrast. Nice find. All we need now is a cheap, magnet based detector so we can find pieces like this.

Seems a lot of this gold in magnetite is found in Australia..

[Jimmy M 150]

Quote

 

I have found specimens of similar gold in magnetite/hematite in the Holcomb Valley near Big Bear California. Van Dusen Canyon in that area is named after Jed Van Dusen, a blacksmith- turned-gold miner during the Big Bear Gold Rush of the 1860's. Claiming that the black sand from Holcomb Valley could be smelted into high grade steel, he urged the miners to sell him their concentrates, from which he secretly extracted the gold. Van Dusen became rich. Nobody knew how or where he got his gold, and when he died there was a great effort put forth to find "Van Dusen's Mine." Since there was no "mine," none was found. Thus the legend developed of "Van Dusen's LOST Mine." BTW nice find! HH Jim

[beatup 215]

what a sweet little specimen

[Nugget Shooter 4,617]

On 1/18/2019 at 6:46 AM, Rob Allison said:

Hey Bill,

   What are you you using for the Macro shot?  A digital camera with Macro or something like a microscope?  Great picture and specimen.  

Thanks for sharing. 

P.S.  A friend of mine stopped using a "super magnet" for this very reason.  He found a small iron/gold specimen on the magnet while he was cleaning it off.  He said he believes he could have tossed many over the course of years of nuggetshooting.  Makes me wonder how many I could have tossed, I always use a very powerful Neo-Nym Super Magnet ..... 

Rob Allison

Hi Rob, I am using a Cannon 850 IS for the close up shots. Have had this camera for many years, small and really good for close up shots.