New Zealand Gold Prospecting & Metal Detecting Forums Archive

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MPS goldhunter		Posted : Saturday, 25 June 2011 11:01:56 AM(UTC)
Rank: Gold Dust Groups: Registered Joined: 13/06/2011(UTC) Posts: 8 Location: Auckland Was thanked: 4 time(s) in 2 post(s)		Greetings all, I recently came across these forums when doing research on gold. I have been studying epithermal deposits of the Hauraki goldfield, Coromandel for 15 years. Unfortunately the goldfield does not have much in the way of alluvial gold and the large nuggets like those of the South Island, but there's some exceptional electrum (gold; silver alloy) in quartz to be seen / found. Like gold panning you certainly get hit by 'gold fever' when finding electrum in quartz. For the last 3 years my research has focussed on fluid inclusions in quartz veins. Fluid inclusions are tiny cavities commonly hosted in quartz that have trapped a small amount of liquid from which the crystal formed. By using different analytical techniques one can determine the temperature at which they formed and the composition of individual inclusions. This is helping better understand how the veins / gold deposits form and hopefully will provide insights as to why some veins are mineralised and others essentially barren. This current year I have been focussing of bonanza grade quartz veins from both the Thames and Coromandel special areas. Unfortunately samples are few and far between and have been a mission to find, but I did get access to some held by the Auckland museum. At some point I should post some images of the bonanza grade samples as well as other vein samples of 'typical' mineralised samples. Anyhow..... I'm keen to make contact with anyone here who has samples from Thames and Coromandel who would like to help in this research. Feel free to make contact below or by private message. Thanks Mark BTW I have attempted panning in the Coromandel with some mates but only found 2 grains of gold

Eagle		Posted : Saturday, 25 June 2011 2:28:30 PM(UTC)
Rank: Gold Nugget Groups: Registered Joined: 3/03/2011(UTC) Posts: 71 Location: Central Otago Thanks: 3 times Was thanked: 15 time(s) in 12 post(s)		Gidday MPS Welcome aboard..very interesting what you are doing. Sorry I can not help you in you research,hopefully someone out there can,I know Colin has a wealth of info. Good luck eagle

Lammerlaw		Posted : Saturday, 25 June 2011 3:20:40 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 24/05/2011(UTC) Posts: 1,721 Thanks: 72 times Was thanked: 579 time(s) in 396 post(s)		Welcome to the forum and hope you enjoy the contents and characters. Would love to see photos of the samples! - I hope they are not too enticing though otherwise I might have to come up that way with some chemical persuasion.

MPS goldhunter		Posted : Monday, 27 June 2011 4:09:07 PM(UTC)
Rank: Gold Dust Groups: Registered Joined: 13/06/2011(UTC) Posts: 8 Location: Auckland Was thanked: 4 time(s) in 2 post(s)		Thanks for the welcome. I'll look to post some images and details of samples tomorrow.

MPS goldhunter		Posted : Tuesday, 28 June 2011 4:27:49 PM(UTC)
Rank: Gold Dust Groups: Registered Joined: 13/06/2011(UTC) Posts: 8 Location: Auckland Was thanked: 4 time(s) in 2 post(s)		Below are some details on fluid inclusions. Fluid inclusions commonly occur in comb quartz like that shown above Vein sample is then prepared as a double polished fluid inclusion plate that is 0.1 to 0.2 mm thick Exampls of exception fluid inclusions which are tiny cavities about 10 microns (or 0.01 mm) in length that have trapped fluid plus a vapour bubble Fluid inclusions can be heated and frozen and this can be used to determine homogenisation temperatures and approximate salinite. The above is temperature data for different sections of the Waiorongomai vein in the Southern Coromandel The chemistry of individual fluid inclusions have been determined at the fluid inclusion lab, Virginia Tech using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)/ pictured above. LA-ICP-MS profile showing the breach of two fluid inclusions and composition Example of ICP-MS results plotted. Hopefully with more research looking at more deposits will get a better idea if the fluids that formed these deposits vary

Lammerlaw		Posted : Tuesday, 28 June 2011 5:06:56 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 24/05/2011(UTC) Posts: 1,721 Thanks: 72 times Was thanked: 579 time(s) in 396 post(s)		Now that is just the cats pyjamas - really interesting stuff and now that you have my undivided attention more more more! I find that really fascinating and always have done so - Although a lot larger I have an enhydro agate and it has never failed to fascinate me. If I had samples like the ones you have, no matter how small, I would find them of great interest and would often be sitting at home here perving at them through the microscope...so your contribution here is genuinely appreciated by me at least.

kiwijw		Posted : Tuesday, 28 June 2011 5:09:10 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 28/03/2010(UTC) Posts: 1,152 Thanks: 92 times Was thanked: 658 time(s) in 324 post(s)		Hi there MPS Goldhunter, Welcome to the site. Now that is something quite different but very interesting. Thank you for sharing. JW :)