Favorable Gold Geology

[Gold Hound]

Most areas I work in have little to virtually no information to reaserch.

The geo maps of the areas have virtually no info on them like faults, intrusions and different rock types.

So I mark all of these features allong with any gold that I find on my GIS mapping software and make my own maps of the area and project the features by studying specialist satellite image's in relation to the information I have obtained by in the field mapping and our gold finds.

This is alot of work but this is why we are so successful.

There is always a reason that the gold is there and there's always an indicator!

It is up to the smart patient prospector to first find the gold, then identify the indicator and project its directon and follow it to more GOLD!!!!

[tvanwho]

I am learning a ton of stuff from a book I bought called:

 

Introductory Prospecting and Mining by Leo and Michael- Mark Anthony, 9th revised edition, 2005. The print is small but readable, tons of info on sampling, various techniques to use including geochemical testing, use of Dip Needles and proton magnetometers to locate placer and magnetic ore bodies, water sample testing to locate ore bodies, resistivity and electrical methods of tracking potential ore bodies. It is targeted to Alaska gold prospectors specifically but lessons learned could apply anywhere. It explains various rock types, just wish it had color photos which it has none of any kind. I am hi-liting things as I read for future reference.

 

-Tom

[Norvic]

Branched from known gold areas, into fringe areas many years back, if I find quartz I concentrate on that area heavily, whether Igneous, Metamorphic or Sedimentary. Have had surprising finds in Limestone, wolfram, coal and tin "country". This has taught me not to be focused on any particular country as Steve`s detailed post points out, even to the extent of stop thinking it`d be better over there where the country "looks better", gold certainly is where it tis and the most distributed  native metal on earth.

Does not take long to detect creeks, alluvial gold can lead to the elluvial gold, which can be multiple signals per swing, this methods is little different  to the original prospectors except the use of detectors rather than pans, GPS`s, moving map software, digital geo, topo maps and our 4WD`s give us a huge advantage. Time positive detecting, lovely finding a creek with nothing but gold signals. I don`t know if this applies to all countries but certainly does to the country I prospect.

[Rege-PA]

Goldhound wrote,   "It is up to the smart patient prospector to first find the gold, then identify the indicator and project its directon and follow it to more GOLD!!!! I have read that some early Australian fossickers followed a black indicator line as thin as a pencil and it would be right off the gold shedding reef, have you ever seen one of these lines? I believe they are a carbon make up.

[Gold Hound]

Goldhound wrote, "It is up to the smart patient prospector to first find the gold, then identify the indicator and project its directon and follow it to more GOLD!!!! I have read that some early Australian fossickers followed a black indicator line as thin as a pencil and it would be right off the gold shedding reef, have you ever seen one of these lines? I believe they are a carbon make up.

The best indicator for gold is.......... GOLD!

I follow the gold to more gold!

There are many many different types of indicator's you need to learn the geology of your area and figure out why the gold comes from were it dose.

Then you can use this knowledge to either follow the geological feature or identify similar feature's.

The indicator could be a fault, quarts reef, iron stone, jasper, chert, grey whack, change in rock type, intrusion, anomoly on a fault like a knee zone, ect ect ect.

For example:

I was detecting up a gully in the middle of no where, when I started to get a fair few small piece's in a run in the narrow gully.

I just kept detecting up the gully and after about 200m the gold run cut out.

But about 50m after my last piece I noticed a diorite intrusion cut across the gully, so I immediately realised that the intrusion is the indicator.

But it was getting late and I had a looooonnng walk back to camp so I decided that I needed to return the next day.

I ended up with 73g in small bits for the day out of the gully bottom.

That night I looked over my Topo's and a couple of specialist satellite images in relation to where I marked the diorite intrusion on my gps software.

I immediately noticed a anomaly on my specialist image that was right near my last nugget in the gully.

So I decided that I would have to have a look at this anomaly that runs parallel to the diorite intrusion but just upstream from my last nugget.

So the next day I returned to investigate the area again.

I went straight to my last nugget location and then hopped out of the gully bottom up on to the steep hill side.

And immediately noticed a narrow arsenic stained quartz reef going up the hill and I also noticed that the soil was slightly different more of a red tinge to it near the reef and on my gps it was exactly on the anomaly that I noticed the night before.

I decided to detect both sides of the gully where the anomaly is and on my first pass after about 30 seconds swinging .......waaaaww.

I got a good strong target in the side of the bank.

After removing about 500mm of over burden I hit bed rock, and the now very loud signal was still in the bottom of my hole in the rock.

So I opened up the hole to make digging the rock easier, after I opened up the hole I could see the arsenic stained quartz reef right where the signal was, so I started to get exited, and started smashing into the rock after about 20 minutes of digging into the rock out poped my first bit of leader gold a bit of rock the size of my fist with about 20g of gold in it after crushing.

I re-scanned the hole, beauty there was still a very strong signal in the hole and a few smaller ones around the edges.

So I kept on digging and after 2 full days busting the rock and removing over burden along the strike of the leader I ended up with 17oz after crushing.

The next thing I did was project the anomaly on my gps and I started working the area near the anomaly.

I picked up good alluvial and elluvial gold following it for nearly its whole length, which was over 5km in length.

What put the gold there?

It was the diorite intrusion.

The diorite when it intruded the older sedimentry rock caused it to fracture in lines parallel to the intrusion, which allowed the gold bearing fluids to deposit the gold where it was.

[Sourdough Scott]

I'm trying to understand the relationship between gold and diorite. I probably seen it a million times, but I thought it was just granite.

[Gold Hound]

I'm trying to understand the relationship between gold and diorite. I probably seen it a million times, but I thought it was just granite.

Diorite is a very hard fine gained igneous rock.

It is usually black or grey and weathers round like granites.

The soil produced by weathering diorite is dark grey and sandy further from the source and very close to the source it can be red/brown.

Re-read my conclusion as to why the gold was there.

Any igneous intrusion in the right country rock can create a auriferous contact aureole.

Some times the aureole can extend for a fair distance from the intrusion.

[Rege-PA]

This is great stuff Gold Hound and it is starting to make sense, but being geologically impaired I realize that I have a long way to go.  Yet you have given me some ideas to use that may put me on to more gold after the first piece is found.  One that comes to mind is recording the elevation of the patch and following that trend around the hill and adjoing areas to see if it outcrops again, also paying attention to the type of rock that the gold is associated with, even if I don`t know its make up.

Need to slow down  and become more observant.

[Gold Hound]

Metal detecting is easy!
Prospecting is a whole other kettle of fish!

To become a proficient prospector takes many many years of hard field work and study.

[Norvic]

I`ll generalise a wee, when detecting you`ll often come across even just a small change in the country, something that is not shown on the geo map. Doesn`t even have to be a mineralised change(but helps), a topo change or even just a vegetation change. Concentrate there too, the main thing is not to dismiss in your mind there is no gold in a particular piece of ground until you`ve detected it. Keep the mind open and have faith in where you are.

In NQ OZ we have a low fine grass nicknamed copper grass, it has a coppery sheen, can be a indicator. But I stress can be, not always same as mentioned in an earlier post, a stand of Cyprus pine can be a indicator. Rege-PA, I have prospected with a couple of Geo`s, and again I`m generalising, they get it wrong too, very good to listen to, to gain knowledge but a closed mind is like waving a detector with a flat battery. There is only one constant, it Tis where it tis, sounds obvious but is true and worth repeating. That field work as Gold Hound mentions is important, but for me, more so than study. I`m definitely geologically impaired.