GeologyRocksAu/Qtz "Pipes" ?
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Hi Dave!
Wed, 01/16/2013 - 01:45Welcome to the group. I'm a fellow prospector located in Colorado, USA.
The only other option I can think of would be drilling core samples, but I doubt that's any cheaper than GPR. If the area was mined before (underground), perhaps there is some information at the local library or a geological survey?
Sounds like an exciting area. Congratulations! Wish I could be more help.
I hope someone on here can answer your questions.
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AuDigga wrote: How does
Wed, 01/16/2013 - 07:51How does fine gold turn into nuggets at the surface ?
Possibly by ionic replacement where molecules attract each other and become concentrated. This was a hypothesis which was put forward to explain concentrations such as yours in Cornwall.
As far as prospecting is concerned, I'm sure Boogie can probably tell you better than me. In my area (Cornwall), lodes and pipes were originally located by trenching and trial pitting. Later on boreholes and trial underground workings were used. However, you will need to do a lot of background research, for example on your batholith and its hydrothermal deposits, to optimise your search locations.
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Hydrothermal deposits
Wed, 01/16/2013 - 22:13Thank Gus
I have have previously asked about nugget formation on various forums but I never received a reply.
I did read an article once that said that there are two types of bacteria that also do the job. Crystaline gold nuggets have been found (detected) in the mud of the Western Australian salt lakes and the W.A. university said that they were formed by bacteria. ?
The big granite Batholith near the source of my gold doesn't have any known gold deposits in it, but many years ago I found a couple of old shallow shafts in the granite. I found their history in old reports. They were mined for cassiterite (Tin) and produced 15 tons of it. I later found a narrow cassiterite vein nearby in the granite that assayed 14% Sn. There is also gold as well as Tin in some of the creeks there, so I guess that there are hydrothermal gold deposits there too ? I suppose I could narrow the sources down with a lot of panning : (
My sister lives in Cornwall and she has sent me several books written by geologist about the Mines there; very impressive ! I will go there for a visit one of these days. Cheers
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Bacteria are thought to be
Thu, 01/17/2013 - 07:47Bacteria are thought to be partially responsible for the deposition of primary deposits in medium to low-grade temperature lodes. Whether they perform much of a role in high temperature lodes (such as tin and tungsten) is debatable but it's possible. It's impossible to replicate the conditions in a laboratory so it's highly speculative. In the oxidized zones of deposits, which is where you get concentrations of minerals such as gold in gossans, it's more likely to be ionic replacement.
If you ever find yourself in Cornwall, send me a PM and we'll arrange to meet if you like.
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Pocket Gold Prospecting
Thu, 01/17/2013 - 19:45Dave, I don't know if this will help you or not, but on the GPAA (Gold Prospectors Association of America) forum, a good fellow named bebarjay posted a thread that describes "pocket gold prospecting". His technique might help you work your situation.
You will need to become a member of the GPAA forum. Then check this thread :
http://www.goldprospectors.org/forum/forum_posts.asp?TID=20591&KW=pocket+placer&title=pocket-gold-prospecting
There is a lot of good information on the GPAA forum, however you need to wade through a bunch of bickering and nonsense to find the good stuff.
Good luck!
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Au/Qtz "Pipes" ?
Submitted by AuDigga on Tue, 01/15/2013 - 07:26.Hello everyone, My name is Dave and I am a 68 year old Aussie Engineering Surveyor and Prospector. This is my first visit to this Forum. I need some advice on locating a high grade gold source on my 6.6 Sq. Km Exploration Licence here in the Northern Territory of Australia. The area was discovered in 1880 and the alluvial gold was worked by about 600 mostly Chinese workers. The source has never been discovered. In its early years it produced nuggets upt 400 ozs in weight and a Au/Qtz specimen that contained 700 ozs of Au. (N.T. Times & Gazette).
Many ounces of gold have been detected since. I let all comers onto my E.L. to detect, under the conditions that they can keep the gold they find, as long as they show it to me and where they found it. This has resulted in them leading me to a fault that starts at the edge of a big granite batholith about 1.5 km away. A high grade (up to 55% Mn) 50cm wide Pyrolusite reef also starts at/near ? the fault under the laterite. The Au/Qtz specimens that we are finding down stream have a typical grade of about 30 % Au. The laterite that starts on the fault is about 80 metres long, 30 metres wide and up to 2m thick. I believe that the source is probably under the laterite. Perhaps close to, or on the fault ? There are no other laterites in the area.
About thirteen years ago in another area 30 km to the north I found a circular Qtz "pipe" after some detecting friends found a number of Au/Qtz specimens. The "Pipe" was 30 cm in diameter. The top 10 cm of it was studded with nuggets. Below that was extremely hard Qtz that had a grade of about one Oz/Ton of extremely fine "mustard" gold. I left it there. The pipe was on a small fault that started at a small Granite intrusion about 100 metres away. (How does fine gold turn into nuggets at the surface ?)
I tend to believe that what I am now searching for will be a bigger "Pipe" under the laterite. Are there any modern methods to locate the source, apart from bringing in a large dozer ? Ground penetrating radar ? All suggestions welcome. Thanks : )