Pictures of GOLD NUGGETS
Largest GOLD NUGGETS ever found – experts say.
NUGGET SENSATION! Discovery of a gold nugget so huge and heavy it took a crane and 10 workers to move (see photo). The nugget took even experts by surprise. Found near Zaamar in Mongolia by veteran geologist Robin Grayson of England, “it was so heavy it broke the springs of my Landcruiser and we had to use a soviet tank transporter to bring it to the city”. The weight is confidential, but experts agree it is expected to set a new world record. FULL STORY bottom of page.
GOLD NUGGETS are often left by gold miners!
Hard to believe, but large gold nuggets are probably more common than most people think. For the last 150 years, gold nuggets bigger than a fist have been screened off and dumped with reject boulders and large stones as ‘washed oversize’. It is rarely economic for a placer gold mine to spend time to look for occasional nuggets, for the real money is made by washing ‘pay dirt’ in a gold sluice or gold jig. Millions of tons of gravel are washed every year worldwide to get the gold but anything larger than 5 to 10 cm is rejected and dumped. That’s why eagle-eyed locals or people with metal detectors can sometimes find a fortune in gold nuggets in such dumps. While a gold wash-plant will catch coarse gold and small nuggets very efficiently and profitably they are not designed to catch fist-sized nuggets. For instance, only a hole in the screen of his New Zealand wash-plant enabled Danny Walker to catch a nugget - read his article. The best way is of course to have a good metal detector, as shown by daily discoveries of gold nuggets in the Gobi by several hundred nomads who earn a good living shooting nuggets - read this article.
How do GOLD NUGGETS form?
The origin of gold nuggets is a matter of debate. Many gold nuggets formed as clusters of gold crystals from very hot water in cracks and fissures in hard-rocks, often with quartz. Later, weathering released the gold nuggets that end up in a stream due to gravity.
But many gold nuggets are found in areas where there seems to be no hardrock gold other than sometimes lots of microscopic gold. Five rival theories then apply, and they might all be right:
1 - Gold nuggets form because gold is malleable, bendable and sticky. During transport small gold particles may stick together or indeed be cold-welded together by pressure and shearing in movement of gravels down a slope or in a stream bed. Shearing and hammering creates a small nugget and then they snowball together by squeezing, hammering and shearing in moving gravels. This sounds impossible but there is a lot of anecdotal evidence for it, such as one of the nuggets shown below. Gold is soft, and behaves like extremely heavy chewing gum that gathers together and sticks together. It is interesting that often gold particles get bigger as nuggets for a few km downstream of the gold source, whereas platinum just seems to get smaller and smaller and platinum nuggets are correspondingly rare – platinum isn’t sticky!
2 - Gold nuggets form because groundwater becomes rich in dissolved gold which sooner or later precipitates in soils and gravels as nuggets. The theory is that the gold precipitates on gold, and so the mass of crystals grows and grows. Now it seems that as well as routine precipitation of gold, the main cause is the role of special bacteria in causing precipitation.
3 - Gold nuggets form from hard-rock gold that is now completely worn away, and so the gold prospector cannot find any evidence of hard-rock gold. It was there, but the evidence has now GONE!
4 - Gold nuggets in modern placers come from old placers being eroded. The older placers, known as paleoplacers might be just a few thousand years old such as river terraces, or be millions of years old. In Mongolia the paleoplacers are Neogene and Cretaceous – read these articles.
5 - Gold nuggets weathered out not from ‘them thar hills’ but from hardrock gold in a zone of weak shattered rock that the stream eroded. Often hardrock gold is missed, being hidden under the placer!
PICTURE OF GOLD NUGGET - found by a Russian bucket-line dredge in the Zaamar Goldfield. The nugget has been battered and smoothed in the river, and consists of gold in cracks in faulted quartzite rock. (photo: Robin Grayson, courtesy of Shijir Alt Company).
COLLECTION OF GOLD NUGGETS - found by the North Dredge and South Dredge in the Tuul Alluvials in the Zaamar Goldfield. By regulation, only melted gold (dore gold) can be sold, and the company does not want to melt these beautiful nuggets. Many of these gold nuggets shown signs of battering, shearing and grinding in the river gravels. (photo: Robin Grayson, courtesy of Shijir Alt Company).
Why bother to describe GOLD?
It astonishes me how few miners describe their gold.
It is worth the effort as it empowers you:
1 – to choose the right gold wash-plant and the right gold prospecting/drilling methods.
2 – to make sense of your gold property and predict where more gold is likely to be.
2 – to look for the gold source – the mother lode!
3 – to predict the geology such as a copper-gold porphyry.
4 – to see if mines left gold behind, such as flat gold.