Post by Admin on Sept 9, 2008 9:10:07 GMT 10
From: brianaurum (Original Message) Sent: 23/06/2008 4:18 PM
Has research been done to tell how far gold has travelled by it's shape, size and roughness etc. If so does anyone have any info on this. Ta
Brianaurum
From: brianaurum Sent: 23/06/2008 4:31 PM
Two quite different shaped bits from the same crevice in a small creek as an example
From: Crusingguru1 Sent: 23/06/2008 5:13 PM
nice bit of gold there Brianaurum
From: ureug1 Sent: 23/06/2008 5:31 PM
Nice gold Brian!!
Not sure about the shape itself, it may say little, except the shape of the vein in the softer host rock before a softer host rock (eg ironstone, pyrites ) was eroded or dissolved away. Quartz is so hard that by the time it has broken perhaps the gold with it may be the fine stuff we see at Eldorado etc.
But I have seen some (eg at Walhalla) from the creek which has sharp & rough edges (much sharper rougher than your nuggets). This to me indicates it has come out of host rock eg a reef (maybe by crushing) and has not traveled far ie is recent.
But a smoother exterior and flattened shape like most alluvial gold in rivers and creeks, shows that the gold has been hammered and edges worn smooth in water by movements against rocks as it has traveled down the waterway or in wet gravel.
Darren, you’re the man, what do you think as a miner who has seen a lot of gold, alluvial and reef?
Eugene
From: Bbbungy2 Sent: 24/06/2008 8:36 AM
Hi Brian.
Two nice pieces mate - one well flattened and the other quite chunky.
Hard to work out isn't it? Looks like both have travelled a little though.
Hope you keep finding plenty more like those.
Regards.
Geoff/bbungy2.
From: reefminer Sent: 24/06/2008 8:45 AM
Hi All,
Its interesting when you have two very different sources of gold concentrated in one area. I have opened up such an area in the Woolshed Valley.
Here is my theory.
The coarse, angular, shotty or whatever you want to call it gold has usually not travelled far from its source and usually indicates a reef deposit nearby. The waterworn gold has travelled some distance from its source hence the rounded shape.
So the two different types of gold in one crevice would indicate to me that it has come from two different sources at two different times.
There are other reasons.
I am currently exploring a deposit where there is a lot of gold, quite angular and hackly as well as quartz reefs in situ that are not waterworn at all. A very short distance away (10 metres) is a buried lead, about 10 feet below the current surface which has significant gold and tin. It is from a much older (Permian) deposit. Above all of this has been a high level terrace which has been heavily worked by the old timers. So you have a mix of recent, old and ancient deposits in one small area and as streams have cut through each type of deposit they have provided some mixing of deposits which would be typical of what Brianaurum has shown.
The Walhalla area and near you Eugene are typical of this as there are reefs shedding into the streams and buried leads crossing the current stream course.
Something I do is to look closely at my pan samples with a 10x magnifier. What may appear waterworn could in fact be quite the opposite.
One theory which I have read considerable text about is the movement of gold nuggets. Many nuggets found in the Golden Triangle appear to be rounded and waterworn. But the gravel and quartz associated with these nuggets shows no sign of water travel whatsoever. The nuggets have not been affected by water but in fact have formed this way. This is all to do with the rate of cooling of the host rock and the gold. This also has a direct effect on the size of the gold pieces.
Rapid cooling of quartz vein means gold is finely disseminated throughout the rock, slow cooling is more likely to form larger nuggets of gold.
A final word on gold particle shape is that water deposition of gold can be slow and gradual or very rapid. This affects size and form of the gold. Remember one thing, The further it travels, the smaller it gets.
Hope this helps a bit.
Cheers,
Darren
From: Banjo520 Sent: 24/06/2008 9:01 AM
Brian nice gold, mate that gold has seen very little movement. James
Reply
Recommend Message 8 of 8 in Discussion
From: brianaurum Sent: 24/06/2008 3:55 PM
Thanks for the reples guys, this gold was some of the gold present in half a bucket of prime crevice wash. A lot more time there has yielded little more in the other crevices so I am puzzled by this. hmmm???
Brianaurum
PS how do you get the emoticons to work in Mozilla?
Has research been done to tell how far gold has travelled by it's shape, size and roughness etc. If so does anyone have any info on this. Ta
Brianaurum
From: brianaurum Sent: 23/06/2008 4:31 PM
Two quite different shaped bits from the same crevice in a small creek as an example
From: Crusingguru1 Sent: 23/06/2008 5:13 PM
nice bit of gold there Brianaurum
From: ureug1 Sent: 23/06/2008 5:31 PM
Nice gold Brian!!
Not sure about the shape itself, it may say little, except the shape of the vein in the softer host rock before a softer host rock (eg ironstone, pyrites ) was eroded or dissolved away. Quartz is so hard that by the time it has broken perhaps the gold with it may be the fine stuff we see at Eldorado etc.
But I have seen some (eg at Walhalla) from the creek which has sharp & rough edges (much sharper rougher than your nuggets). This to me indicates it has come out of host rock eg a reef (maybe by crushing) and has not traveled far ie is recent.
But a smoother exterior and flattened shape like most alluvial gold in rivers and creeks, shows that the gold has been hammered and edges worn smooth in water by movements against rocks as it has traveled down the waterway or in wet gravel.
Darren, you’re the man, what do you think as a miner who has seen a lot of gold, alluvial and reef?
Eugene
From: Bbbungy2 Sent: 24/06/2008 8:36 AM
Hi Brian.
Two nice pieces mate - one well flattened and the other quite chunky.
Hard to work out isn't it? Looks like both have travelled a little though.
Hope you keep finding plenty more like those.
Regards.
Geoff/bbungy2.
From: reefminer Sent: 24/06/2008 8:45 AM
Hi All,
Its interesting when you have two very different sources of gold concentrated in one area. I have opened up such an area in the Woolshed Valley.
Here is my theory.
The coarse, angular, shotty or whatever you want to call it gold has usually not travelled far from its source and usually indicates a reef deposit nearby. The waterworn gold has travelled some distance from its source hence the rounded shape.
So the two different types of gold in one crevice would indicate to me that it has come from two different sources at two different times.
There are other reasons.
I am currently exploring a deposit where there is a lot of gold, quite angular and hackly as well as quartz reefs in situ that are not waterworn at all. A very short distance away (10 metres) is a buried lead, about 10 feet below the current surface which has significant gold and tin. It is from a much older (Permian) deposit. Above all of this has been a high level terrace which has been heavily worked by the old timers. So you have a mix of recent, old and ancient deposits in one small area and as streams have cut through each type of deposit they have provided some mixing of deposits which would be typical of what Brianaurum has shown.
The Walhalla area and near you Eugene are typical of this as there are reefs shedding into the streams and buried leads crossing the current stream course.
Something I do is to look closely at my pan samples with a 10x magnifier. What may appear waterworn could in fact be quite the opposite.
One theory which I have read considerable text about is the movement of gold nuggets. Many nuggets found in the Golden Triangle appear to be rounded and waterworn. But the gravel and quartz associated with these nuggets shows no sign of water travel whatsoever. The nuggets have not been affected by water but in fact have formed this way. This is all to do with the rate of cooling of the host rock and the gold. This also has a direct effect on the size of the gold pieces.
Rapid cooling of quartz vein means gold is finely disseminated throughout the rock, slow cooling is more likely to form larger nuggets of gold.
A final word on gold particle shape is that water deposition of gold can be slow and gradual or very rapid. This affects size and form of the gold. Remember one thing, The further it travels, the smaller it gets.
Hope this helps a bit.
Cheers,
Darren
From: Banjo520 Sent: 24/06/2008 9:01 AM
Brian nice gold, mate that gold has seen very little movement. James
Reply
Recommend Message 8 of 8 in Discussion
From: brianaurum Sent: 24/06/2008 3:55 PM
Thanks for the reples guys, this gold was some of the gold present in half a bucket of prime crevice wash. A lot more time there has yielded little more in the other crevices so I am puzzled by this. hmmm???
Brianaurum
PS how do you get the emoticons to work in Mozilla?