BrokeInBendigo

QGIS with govt-provided datasets and georeferenced old maps. A bit technical to set up but hard to beat. Tumonz also great, though I've not seen the latest versions.

That intro video is hilarious. Like comically overblown hype with similarly comically bad CGI. Lol! Guess the coin and relic crowd is a bit different than the gold crowd.

Maybe a tiny amount of material would leach out but only the outermost molecules in the nugget would be exposed to the environment. I'm more referring to the depositional environment - the bedrock or clay or whatever acts just like a sluice to catch gold particles. It also catches heavy materials like iron-rich minerals. Those other materials are concentrated along with the gold contribute to the response. When you dig, you disperse all the other stuff and the response is no longer the both gold + nearby concentrated minerals, it's mostly just the gold, hence a lesser response.

Nugget halo makes sense to me. You'd expect iron-containing heavy minerals (ground noise) to settle in along with nuggets. It's not that the gold itself is interacting with its environment, but that the process that guides nuggets to their resting place also accumulates materials that give a bit of a signal. When digging, you break up the previously concentrated and defined volumes of metalliferous material which surrounded the gold. I'd be confused if a nugget in its "original" spot *didn't* sound different than the same nugget buried at the same depth, with same orientation, in the same now-disturbed ground.

Talk about Real Hard Yakka™️ country! I suppose prospecting style picks will do pretty well on ice.

A major lesson learned after moving to Australia is that friends here use words that, in the states, you don’t even use for enemies (much less suitable for this forum). JP’s post was actually quite warm and fluffy relative to the usual vernacular.

Gerry, Might wanna slow down there buddy. There are some older folks on this board that need to watch their blood pressure.

Great results Simon. I expect ML will replace the 11" coil. Hopefully they take responsibility on a larger scale for the apparently quality issues with the coil and detector.

Thanks for your detailed posts JP.

Thanks JP. I have a stock 14” and month-old 17” CC x-coil, believe it is bundle wound (edit: tis spiral, thanks Simon). Out bush in reefy country with a lot of ironstone or red mudstone type bedrock I often get a fairly loud signal on the ferrite but on alluvial gravels or paddocks it’s less intense. I’ve been running auto but understand the advantage of semi auto - I’ll try that and your suggestion about elevating the ferrite today.

I can "balance" the ferrite out in Difficult using the QT button but cannot balance it out in Normal. I've done the octopus (as described by @Jonathan Porter ) manoeuvre for 1 to 2 minutes over the ferrite, still hear it. Especially if the ground is hot. Am I doing it wrong?

This is the big shift with machine learning (what we are, for convenience, referring to as "AI"). Computers are no longer only as good as the programmer. Computers are better than the programmer - much, much better. Perhaps disturbingly, the programmer has no functional access to the logical process an AI uses to make a given decision. It is too complex and abstract, humans generally cannot understand it, despite being able to analyse that decision-making process. Put a coil on an AI and you could have a detector that rivals and even surpasses the work of human genius. Just one example of machine learning revolutionising a data analysis problem (which humans have spent a very significant amount of time and money on): https://www.escardio.org/The-ESC/Press-Office/Press-releases/machine-learning-overtakes-humans-in-predicting-death-or-heart-attack

Here's a moderately technical paper from Minelab (who, at this time, makes the best pulse induction prospecting detectors): https://www.minelab.com/__files/f/11043/KBA_METAL_DETECTOR_BASICS_&_THEORY.pdf More basics (see Multi Period Fast, Multi Period Sensing, Smart Electronic Timing Alignment, Zero Voltage Transmission): https://www.minelab.com/anzea/knowledge-base/key-technologies Some good info in there. Minelab does use multi-frequency TX and RX but their analysis is magic sauce. Imagine they have some sophisticated analysis. As you well know, if there was AI involved anywhere, their marketing would ensure we know allll about it. Alternative avenues of improvement include ZVT (as mentioned above, this was the main innovation in the GPZ 7000, released 2015, new updated model on same platform expected in the relatively near future) and innovative coil design (for example, the recent rise of concentric coils for the GPZ, some recent patents for coils in which a flat-wound coil is twisted at front and rear to be vertically oriented, to reduce saturation from ground mineralisation and other designs).

Exactly. Your experiencing running with GB off illustrates how much detecting depth depends on the ground handling. Think I’d still rather have our Aussie sized nuggets and hotter ground than your mild soils and fine gold 😅 hope you can make it over here some time for a prospecting adventure and smash some personal bests!

Simon’s referring to no ground balance at all - not fixed/manual GB - which is a setting I’d wager nobody uses on Australian goldfields.