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Gold Prospecting
Metal Detecting for Gold
Difference Between Shallow Workings And Shallow Leads.
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<blockquote data-quote="user 4386" data-source="post: 485080" data-attributes="member: 4386"><p>So long since I have worked there that one should check all access legalities (I don't know the nature of those extensive reserves). Used to be good. Tarnagulla had one of Victoria's richest gold-quartz mine for a bit, averaged 3 oz per tonne. Everyone knows the nuggets of Poseidon (but boy, has that been done over since).</p><p></p><p>Here is a cross-section of a deep lead alluvial gold mine. You can see the problem - only the gravels at the bottom have significant gold, so there are few places at surface where you can detect. On the right are older, uplifted gravels (an ideal place to detect). Where the leads are shallower they may lack the basalt on top, but in flatter areas it is still up to 30 m down to the top of the gold-bearing gravel (so same problem - detecting on those overlying clays, or around the modern river, will achieve little). An important point - nearly all significant alluvial gold in Victoria was NOT associated with modern rivers - for reasons you can see, many big rivers were quite barren e,g, the Loddon River). Hope that helps. A few were productive (eg the Lerderderg) but the overall ounces out of the river itself even there was miniscule compared with surrounding shallow leads and quartz veins (it cut a gorge so cut through gold-quartz veins in bedrock, which put some gold into the modern river). Most deposits were formed in rivers that existed 22 million years ago (those shown as uplifted are probably 35 million years (My) old - not as rich as the 22 My group, nor as extensive, but still locally productive in fields like Ararat and Stawell.</p><p></p><p><img src="https://www.prospectingaustralia.com/forum/img/member-images/4386/1555832388_deep_lead_gravel.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="user 4386, post: 485080, member: 4386"] So long since I have worked there that one should check all access legalities (I don't know the nature of those extensive reserves). Used to be good. Tarnagulla had one of Victoria's richest gold-quartz mine for a bit, averaged 3 oz per tonne. Everyone knows the nuggets of Poseidon (but boy, has that been done over since). Here is a cross-section of a deep lead alluvial gold mine. You can see the problem - only the gravels at the bottom have significant gold, so there are few places at surface where you can detect. On the right are older, uplifted gravels (an ideal place to detect). Where the leads are shallower they may lack the basalt on top, but in flatter areas it is still up to 30 m down to the top of the gold-bearing gravel (so same problem - detecting on those overlying clays, or around the modern river, will achieve little). An important point - nearly all significant alluvial gold in Victoria was NOT associated with modern rivers - for reasons you can see, many big rivers were quite barren e,g, the Loddon River). Hope that helps. A few were productive (eg the Lerderderg) but the overall ounces out of the river itself even there was miniscule compared with surrounding shallow leads and quartz veins (it cut a gorge so cut through gold-quartz veins in bedrock, which put some gold into the modern river). Most deposits were formed in rivers that existed 22 million years ago (those shown as uplifted are probably 35 million years (My) old - not as rich as the 22 My group, nor as extensive, but still locally productive in fields like Ararat and Stawell. [img]https://www.prospectingaustralia.com/forum/img/member-images/4386/1555832388_deep_lead_gravel.jpg[/img] [/QUOTE]
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Gold Prospecting
Metal Detecting for Gold
Difference Between Shallow Workings And Shallow Leads.
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