Wahgunyah often gets left out of the Indigo story but when gold was discovered near this site in September 1860 it was initially known as the Wahgunyah Diggings.
The gold rush that took place here was one of the last Victorian gold rushes; the Wahgunyah diggings followed deep alluvial leads. Gold miners extracted gold from wash dirt brought up from the ancient riverbeds deep underground. Rich quartz reefs were discovered. By the end of 1860 17 deep leads and seven quartz reefs had been found. Mullock-slime dumps, Mullock heaps, Tailings and Towns that no longer exist are strewn across the district as a reminder of times of past giving area its unique landscape. As a child I can remember Opium poppies growing along the Murray river near Wahgunyah which were said to be remnants form the Chinese miners.
The coordinates for this EC will have you standing at Rutherglen State Battery, which was operational from 1908. It is one of six intact former State batteries situated in Victoria. This site was close to the Rutherglen Quartz Mine and surplus water from the mine was used by the battery. The Battery requires 3000 gallons of water to crush 10 tons of quartz.
Gold is a chemical element with symbol Au and atomic number 79. It is the only yellow metal it is very dense, soft, malleable and ductile, these properties remain when exposed to air or water and is solid under standard conditions. The metal therefore occurs often in free elemental (native) form, as nuggets or grains, in rocks, inveins and in alluvial deposits. It occurs in a solid solution series with the native element and also naturally alloyed with copper and palladium.
A popular misconception is that natural gold has cooled from a molten state. I’ll admit it when I started on this Earth Cache that is what I thought. In actual fact, gold is transported though the Earth’s crust dissolved in warm to hot salty water.
For the full article please Click here to go to the geocaching resource site.
The condensed version of events are: These fluids are generated in huge volumes deep in the Earth’s crust as water-bearing minerals dehydrate during metamorphism. Any gold present in the rocks being heated and squeezed is sweated out and goes into solution as complex ions. In this form, dissolved gold, along with other elements such as silicon, iron and sulphur, migrates wherever fractures in the rocks allow the fluids to pass. This direction is generally upwards, to cooler regions at lower pressures nearer the Earth’s surface. Under these conditions, the gold eventually becomes insoluble and begins to crystallise, most often enveloped by masses of white silicon dioxide, known as quartz. This association of gold and quartz forms one of the most common types of "primary gold deposits". As chemical weathering and erosion gradually break down the host rocks in this case Quartz and gold are then exposed.
The gold veins provide far more resistance to chemical attack than the surrounding rocks, so that mechanical weathering is required to fragment the quartz, thereby releasing the gold. Because they are relatively heavy, particles of gold are more difficult to move and so become naturally concentrated in the soil or in adjacent gullies or streambeds. These concentrations are known as alluvial deposits. Alluvial deposits take many forms, including sands and gravels in the beds of modern-day streams, in old river valleys buried under lava flows or perched on hilltops due to uplift of the land surface.
Quartz is the second most abundant mineral on earth. It occurs in many different forms some of which are semi precious gem stones, Smokey quartz and Rose quartz are two of these and can be found not too far away in the hills around Beechworth. The quartz in this area is referred to by locals as White Quartz or Rusty Quartz, you will notice it has Rusty Iron staining giving it its unique character. It isn’t as ascetically beautiful as quartz in its opaque crystal form. The white colour is caused by minute fluid inclusions of gas, liquid, or both, trapped during the crystal formation causing cloudiness.
Quartz is an essential constituent of granite and other felsic igneous rocks. It is very common in sedimentary rocks such as sandstone and shale and is also present in variable amounts as an accessory mineral in most carbonate rocks. It is also a common constituent of quartzite and other metamorphic rocks. Because of its resistance to weathering (its very hard) it is very common in stream sediments and in residual soils. While the majority of quartz crystallizes from molten magma, much quartz also chemically precipitates from hot hydrothermal veins as gangue, sometimes with ore minerals like gold, silver and copper. Large crystals of quartz are found in magmatic pegmatites. Well-formed crystals may reach several meters in length and weigh hundreds of kilograms.
To successfully log this Earth Cache please message us the following answers: ( If you would like to do a basic log to keep your stats and TB distance in order that is fine, but failure to message us the correct answers within 24 hours of such a log will result in the log being deleted.)
1. Pick up a piece of Quartz and examine it, does it feel ‘rock hard’ is it crumbly or hard?
2. Are there any other colours present in the Quartz what does this suggest?
3. Can you see any crystals in the quartz?
4. A photo of your team or GPS with the site in the background.
*It is not necessary for the site to be 'open' to complete this EC*
We hope you have enjoyed this earth science lesson as much as we enjoyed putting it together we look forward to reading your log.
*A big thank you to Bingley3683 for his assistance with coordinate gathering after I lost my initial EC notes.
Additional information:
http://www.beechworth.com/visitor_information/brochures/gold_trail.pdf
http://en.wikipedia.org
http://www.goldrushcolony.com.au/australian-gold-history-culture-info/gold-all-about-gold/alluvial-gold-and-its-recovery
http://www.sbs.com.au/gold/story.php?storyid=128
