T2 hunting for gold (nuggets) vs hotrocks

[Ben78]

I previously owned a Gold Bug Pro but replaced it with a T2 as the T2 gets better depth on silver coins. I only parted with the GB once I knew that the T2 responded well to nuggets which is does. I have a 8 grain nugget that the T2 will pick up at 6" with the 11" DD coil.

The problem I am having is the constant noise from ground and hotrocks. Everything I read says that a hotrock will sound like a boing and the nugget will be a zip zip. Problem is that I am getting the same sound for rocks as I am for the nugget. Not quite a boing, not quite a zip - still a tight sound, much like a coin at 6". It is truly driving me to distraction. I am to the point that I am looking at the Whites TDI to use for nugget hunting and the beach (somewhere else the T2 is lacking...)

Has anyone got any tips for hunting nuggets with a T2?

I love this machine compared with the Gold Bug, it rakes in the park silver in but I want it to get the creek gold too.

Settings...
T2 (standard)
11" and 5" DD Coils
All Metal Mode
Sensitivity @ 75
Hum @ +1 (factory setting)
GB is around 55-62 depending on whether the coil is in water, out of water or up on the bank.

When I get a signal I pump the coil over it to see if the FeCo meter goes up. It usually does - but it also does on my test nugget...

(dreaming of a minelab destroying Teknetics discriminating PI )

 

[Dave J.]

http://www.tekneticst2.com/tekfiles/Dave%27sGoldbook-reders.pdf

 

[Monte]

Okay, it is kind of simple, and becomes much easier as we learn to better handle our detector, better deal with the ground mineral environment, and start recovering more tell-tale signs that we have it all figured out.

I previously owned a Gold Bug Pro but replaced it with a T2 as the T2 gets better depth on silver coins. I only parted with the GB once I knew that the T2 responded well to nuggets which is does. I have a 8 grain nugget that the T2 will pick up at 6" with the 11" DD coil.

I previously had the T2 and replaced it, for nugget hunting, with the G2. The same models as the Gold Bug Pro, and it compliments my other-brand nugget hunting model (a White's MXT Pro).

The problem I am having is the constant noise from ground and hotrocks.

'Ground' will produce a signal of about 1 Hz to 2 Hz. We can usually deal with the ground signal by using a proper Ground Balance and have the assistance of an auto-tune circuitry. Rapidly changing ground, however, can cause us more problems. Often, the main thing we can do is ensure we have a proper Ground Balance, and also reduce the gain (Sensitivity) a little if we need to.

As for Hot Rocks, remember that there are two classes of Hot Rocks and that is really determined by the ground we are hunting and our Ground balance setting. Refer to the link Dave J. posted, and read Page 14 and the first half of Page 15.

Everything I read says that a hot rock will sound like a boing and the nugget will be a zip zip.

A smaller nugget will produce a 'zip' sort of sound, especially if the detector has a fast auto-tune speed. The 'boing' sound you hear is from the 'Cold Rocks' and those are basically rocks with a greater or higher mineralization value that the GB established for the surrounding matrix. Thus, when you sweep across them the Threshold will null, quickly, and then the over-shoot as it tries to restore the Threshold audio can produce a 'boing' type audio after you sweep past the rock. This makes a 'boing' on either side of the rock and that's partly based upon the coils size and type, the amount of differences between the Cold Rock's value and the GB setting use, and then it also depends upon the sweep speed you use.

Problem is that I am getting the same sound for rocks as I am for the nugget. Not quite a boing, not quite a zip - still a tight sound, much like a coin at 6". It is truly driving me to distraction. I am to the point that I am looking at the Whites TDI to use for nugget hunting and the beach (somewhere else the T2 is lacking...)

Small rocks that are just a bit less 'bad' mineral than the GB setting for the surrounding ground means that your GB setting is now slightly positive for that rock. Thus, you hear a small 'zip' sound response to that rock that can be similar to a small response to a little gold nugget.

Has anyone got any tips for hunting nuggets with a T2?

Yes, I have. It can do okay, and it quite popular in many foreign countries for just that need. That said, there are three metal detectors that I personally like and own, or have owned, for gold nugget hunting. One is my White's MXLT Pro. The MXT was a design by Dave J. The other, and I don't have it in my personal arsenal but am looking for a choice specimen, is a Tesoro Diablo

 

[Ed in SoDak]

Another way to test for hotrocks is to pump or bob the coil at them. A normal target will sound as the coil approaches it. A hotrock will sound when the coil is pulled away from the rock.

The soil here is infested with small patches of native iron bits. Individually, they're too weak to detect, but in a cluster they'll sound off as a positive target. They detect much like a small nugget might, but ID as iron. The sound in all metal sort of trails off as the coil moves away, while a good target has a sharper, more abrupt end to the tone.

If I put my test nugget nearby and check both the iron patch and the nugget, the subtle difference between them becomes more apparent.

-Ed

 

[Ben78]

Thanks Monte, Dave and Ed.

I guess I just need to spend more time in the field. Can get very tiresome getting half a dozen sounds identical to my nugget in every swing. I only concentrate on the tight sounds and still end up with rocks.

Ed, my test nugget IDs as a '9' on the T2 when I am in the field. Bench testing its closer to 50...

I sold the Gold Bug as I didn't really have a need for a second detector and the T2 gave a better response on the test nugget than the Bug. I will miss the ground phase readout on the Bug though, when it dropped fast you knew it wasn't a rock!

Ben

 

[Monte]

Another way to test for hotrocks is to pump or bob the coil at them. A normal target will sound as the coil approaches it. A hotrock will sound when the coil is pulled away from the rock.

The "hot-rock" that produces that response is actually a 'Cold Rock' which nulls as the coil is lowered and responds when the coil is lifted away. That's because the GB setting is negative for that rock. In general sweeping, that would produce the 'boing' sound on a motion-based All Metal unit (fast auto-tune function).

The soil here is infested with small patches of native iron bits. Individually, they're too weak to detect, but in a cluster they'll sound off as a positive target. They detect much like a small nugget might, but ID as iron. The sound in all metal sort of trails off as the coil moves away, while a good target has a sharper, more abrupt end to the tone.

Those are the little 'Hot Rocks' that faintly respond as they are just a bit less mineralized than the surrounding ground (making the GB slightly positive) or are just tiny, low-conductive samples.

If I put my test nugget nearby and check both the iron patch and the nugget, the subtle difference between them becomes more apparent.

You're right there and I think it takes a good gold nugget sample, or something similar, to learn to hear the difference in audio response for those tiny hot rock issues.

Monte

 

[Ed in SoDak]

I've been perplexed by the geology involved and trying to learn more as I read about gold deposits that are associated with native iron. I have the geo map and report plus mining reports for this gulch and the surrounding area. It's very complex to say the least, but there is scant mention of the iron deposits, so I'm left to my own devices to learn what I can about them. This gulch was home to nearly all the mines in the area that were big enough to have a recognizable name and earn a listing in the geologist's reports.

The offshoot is that I'm looking for free gold in quartz or as residual placer deposits associated with the known faults, veins and historical mines. But I'm constantly running into these iron signals instead. I've found solid metal pieces large enough to be meteorites, but there are also irony slates with enough metal to stick to a magnet.

Fortunately, they have proven to be identifiable by a couple of their characteristics. One is the depth reading always says 6 inches and it drifts around, never actually showing a definite pinpoint. A nugget will get louder as you get closer to it and will have a pinpointable response. The larger chunks have a true iron signal.

My test nugget is only 2.2 grains. I figure that's closer to reality of what I may find, especially since it did come from a nearby claim a friend of mine works that is known to produce surface nuggets.

The disseminated iron clusters probably have that trailing off sound because they are small and diffuse in the soil. I'm not sure if the positive signal is due to being "less mineralized" or they simply have so much iron they read due to metal content.

Just to make things more interesting, they will drag down the ID of any object that happens to be among them or above. Coins will drop a full ID range, but bobbing the coil over the signal will show up what's going on. It's taken serious testing to discover some of this. The funny part about that was I learned most of it by trying to create a test garden in my yard in order to so some testing of a number of different detectors. That was when I discovered I couldn't find a clear spot in my yard that didn't have these iron patches. I ended up having to more or less incorporate the iron patch response as a part of my testing logs.

I don't see many rocks with a "cold rock" or null-type response around here. The best samples I have for cold rocks are stony-iron meteorites and I've done extensive testing which I posted here: http://www.whiteriverprep.com/meteor/meteor.html

What I found out about meteorites is also true for detecting gold nuggets. The best test object is an actual sample of what you're looking for.

It does get frustrating with these nuisance signals that waste your time while hunting for gold. But with practice, I am learning how to ID them better.

-Ed

Here's some samples of the iron I've found in my yard and the surrounding mountains.

 

[markg]

"Yes, I have. It can do okay, and it quite popular in many foreign countries for just that need. That said, there are three metal detectors that I personally like and own, or have owned, for gold nugget hunting. One is my White's MXLT Pro. The MXT was a design by Dave J. The other, and I don't have it in my personal arsenal but am looking for a choice specimen, is a Tesoro Diablo