Paper written for non-geologists describing Victorian gold deposits - email copies.

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Goldierocks,
Great info thanks for sharing,
Can you send me paper on vic gold deposits.
I have not made 10 posts yet so cant PM
My email --not allowed open forum.

Thanks
Michael
 
staples61 said:
Goldierocks,
Great info thanks for sharing,
Can you send me paper on vic gold deposits.
I have not made 10 posts yet so cant PM
My email --not allowed open forum.

Thanks
Michael
Michael, I can't because too large to send as an attachment - need email to send you to download site. Contact me when you can PM.
 
I think you still have the option to email me if you want to (see button) just not PM
 
Goldilocks thanks for sharing your knowledge. Truely remarkable!
I would love to be able to read the article you speak of. I dont know how to personal msg though or send you a email from this forum?
 
Aintnothingbutagolddigger said:
Goldilocks thanks for sharing your knowledge. Truely remarkable!
I would love to be able to read the article you speak of. I dont know how to personal msg though or send you a email from this forum?
I think you need 10 posts, then you can PM me.
 
I can fully appreciate that problem - much of the first year of a geology degree involves learning terminology. But possibly you are reading the wrong books. First you need to get a very basic background in geology overall - the ideas of igneous, sedimentary and metamorphic rocks and folding (deformation) of rocks - faults and folds. Then understand the difference between a chemical element (about 92 occur naturally), componds (=minerals) and rocks. Elements combine with each other to form chemical compounds. For example copper and oxygen combine to form the compound copper oxide - copper, oxygen and carbon combine to form the compound copper carbonate.

Chemical compounds that are not organic and that occur naturally in nature are what we call minerals - because they often crystallize slowly this can result in large and beautiful crystals. Each mineral is defined by two things - not just its chemical composition but also its crystal structure (the way its atoms are arranged internally within the crystal). So graphite and diamond are both the element carbon, but are different minerals because they have quite different crystal structures (which gives them different hardness, colour, lustre, specific gravity etc.). Calcite and aragonite are both calcium carbonate, but because they have different crystal structures they are two different minerals. We also simplify terminology by grouping minerals with related characteristics - the pyroxene group includes many minerals (augite, diopside), similarly the amphibiole group (hornblende, tremolite, actinolite, even blue asbestos), or the garnet group (almandite, grossularite etc.), or the epidote group (epidote, zoisite, clinozoisite).

Gemstones and precious stones are simply pretty minerals. The names are sometimes not made up by geologists but can be invented by dealers or companies as an aid to marketing. Geologists invented names like ruby and sapphire for red and blue versions of the mineral corundum, and emerald and aquamarine for beryl minerals that have those colours. But the list is endless - quartz gem minerals (citrine, cairngorm, amethyst, agate, chalcedony), or recent additions (tanzanite - a beautiful form of epidote from Tanzania, tsavorite - beautiful green garnet from Tsavora valley, also in that country).

Rocks are mostly just substances built of more than one mineral. So granite is usually biotite+feldspar+quartz (but never olivine) - basalt is often olivine+pyroxene+feldspar (but never quartz). However some rocks are simply made of huge numbers of grains of a single mineral (sandstone is quartz grains, limestone is calcite grains). So you could say that almost all rocks are built of multiple grains of minerals.

Then you need to understand that some minerals separate out of molten rocks, but many crystallize from water solutions. So many non-geologists think that gold-bearing quartz veins are "intruded" into faults in rocks as some sort of molten goo. They do not - they simply crystallize slowly on both walls of the fault from a dilute hot water solution that is flowing through the open fault cavity, until finally crystals grow all the way to the centre giving a sealed vein, and further flow of water is blocked. That is why you often see crystals and open cavities in the centre of quartz veins - bits that were not completely blocked and closed off. If you watched a quartz vein forming, you would see an open fracture, a layer of quartz on each wall, and very hot clear water pumping through between the walls.

Sometimes minerals crystallize from quite cool water (but may still be large crystals), and other minerals are altered by rain and atmosphere close to surface to crystallize as new minerals. So a quartz vein that contains copper sulphide minerals at depth (e.g. chalcopyrite, chalcocite, covellite) will alter near surface by reaction with oxygen in the atmosphere to form things like copper oxide (cuprite) or copper sulphate (chalcanthite); they also react with carbon dioxide in the atmosphere to form copper carbonates like malachite and azurite. So these minerals form at the top of ore bodies, close to surface. Many prospectors know that ironstone and quartz often occur together - one reason is because the quartz probably contains pyrite (iron sulphide) at depth, but this reacts with oxygen in the atmosphere near surface to give iron oxide (eg the mineral limonite or goethite).

Many people assume that gold cannot dissolve in near-surface cold water, Incorrect. In desert areas, the water is often highly saline (e.g. tens of percent dissolved salt - ordinary table salt in composition). Gold dissolves readily in this near the surface, where there is also plenty of atmospheric oxygen. The dissolved gold then moves through the soil in groundwater and weathered rock until it meets up with some carbon or iron, then it dumps out again as metallic gold, sometimes as nuggets (so some gold nuggets actually form in the soil). The original gold may have a lot of contained silver, but the new gold in the soil is almost pure gold.

There is a paper written for non-geologists that describes Victorian gold deposits. Anyone who PMs me with an email address can have a download.
Hi there goldi
 
Hi Goldierocks, I would like to put my hand up for a copy as well.
As a newby I think the ten posts rule might stand in the way.
I will post.
Thank you, Manoli
 
As noted above, I can only provide as email copies.
Most requests have not included an email address to send to.
 
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