Metal detector & pyrite...and eventually gold

Eric Foster

Newbie
Nov 19, 2007
1
0
Re: Metal detector & pyrite...and eventually gold

Hello,

Iron Pyrites is a difficult metal to detect because of its low electric conductivity. One detector that I know works is the Fisher Goldbug 2. I have some pyrite cubes from Northern Spain and the GB2 will detect these OK provided more than 1/2in cube. You definitely need a high frequency detector and the GB2 runs at 70kHz.

Eric.
 

El Cooter

Full Member
Mar 20, 2007
201
3
Merced, Ca.
Detector(s) used
Whites XLT, GMT, V-Sat and ML2200d
Primary Interest:
All Treasure Hunting
Re: Metal detector & pyrite...and eventually gold

He would know!!
 

nuggetshooter323

Hero Member
Jul 22, 2005
963
869
Colorado Springs
Detector(s) used
The Legend, Anfibio Equinox 900, Gold Kruzer, XP Deus, ORX, Tesoro Tejon, Whites GMT, Falcon MD20, XP MI-6, Fisher F-Pulse, Pulse Dive, Vibra Probe, UniProbe.
Primary Interest:
Prospecting
Re: Metal detector & pyrite...and eventually gold

I have a Lobo Super Traq and it works at 17.5 khz, and it doesn't utter a peep with pyrite, which is just fine with me. Now I have a Falcon MD20 probe, and it works at 300 khz, and it also doesn't utter a peep with pyrite. Why does the GB2 sound off at 70 khz with pyrite?
 

Jim Hemmingway

Hero Member
Jan 26, 2008
788
1,615
Canada
Detector(s) used
F-75, Infinium LS, MXT, GoldBug2, TDI Pro, 1280X Aquanaut, Garrett ProPointer
Primary Interest:
Prospecting
Re: Metal detector & pyrite...and eventually gold

Hello SSR60,

I checked out two iron pyrite (iron sulphide) samples in both true all metal mode, and in zero discriminate mode on my Spectrum XLT (frequency somewhere around 6.6 kHz..I can't remember exactly, but it"s close enough...it's low frequency, coil size nine and one half inches). The auto track was turned off, and the detector was manually ground balanced to about minus 93 VDI (-93) out in my patio....with the samples laid on the frozen ground (that ground balance implies pretty tough mineral background ie close to black sand). Disc Sens @ 64 out of 80, All Metal Sens @ 48 out of 60....modest sensitivities.
(a) the first sample, about two inches long by an inch and a bit in diameter/width gave no reading at all. Nothin'.
(b) the second sample, about two and a half inches by two inches in diameter/width gave a reading that fluctuated between minus two (-2) and plus four (+4) VDI, in both modes (entering the lower foil range).

In either mode the audio response was quite weak, the sample could only be detected approx. two inches from the coil. In discriminate mode, the audio signal was broken (not diggable), while the all metal signal was smooth and clear.
The above VDI range is about what you would expect from low grade silver ore (with bits of native silver showing from low conductive arsenic-cobaltite mix in calcite), but the difference is that same size low grade ore gave off a much more powerful signal and could be detected out to about 10 inches. Thus, a good sized sample of pyrite can be detected with a lower frequency detector, but it's a real low power conductive, implying you must get the coil close to it in order to detect it. Fortunately, some pyrite dumps offer good pickings right on the surface. If you want to hunt this stuff, take Eric's advice above. Hope this helps.

Follow up: A couple of interesting bench test points (a) as the XLT ground balance was decreased from a black sand level to lightly mineralized ground conditions, the pyrite response in all metal gradually diminished to a point where it no longer responded with an audio signal (b) using the Goldstinger, operating @ 15kHz, coil size @ 8 inches, all metal mode @ about 80% sensitivity, both pyrite samples were easily detected, the larger piece out to three and one-half inches easy. It did not matter whether the ground balance was set to black sand, or reduced to light mineralization, the response was pretty much the same throughout the entire span; a slight diminishing of signal strength as salt ground balance was approached (c) the overall signal strength was considerably stronger with the Goldstinger compared to the lower frequency XLT.
That's it I guess, you made me curious too...so long...Jim.
 

UncleVinnys

Bronze Member
Dec 27, 2007
1,150
170
Hancock Street, Folsom, CA
Detector(s) used
Minelab Equinox 600
Re: Metal detector & pyrite...and eventually gold

nuggetshooter323 said:
I have a Lobo Super Traq and it works at 17.5 khz, and it doesn't utter a peep with pyrite, which is just fine with me. Now I have a Falcon MD20 probe, and it works at 300 khz, and it also doesn't utter a peep with pyrite. Why does the GB2 sound off at 70 khz with pyrite?

Greetings . . . I just got the Falcon MD20 too, and was VERY IMPRESSED at its
super sensitivity. I tune it to just under oscillating, and I swear you can pick up
the earth's magnetic field by twirling that thing around !!! . . .
Anyway, I'm wondering how you use it, how it is used in conjunction with the
detector or by itself??
 

nuggetshooter323

Hero Member
Jul 22, 2005
963
869
Colorado Springs
Detector(s) used
The Legend, Anfibio Equinox 900, Gold Kruzer, XP Deus, ORX, Tesoro Tejon, Whites GMT, Falcon MD20, XP MI-6, Fisher F-Pulse, Pulse Dive, Vibra Probe, UniProbe.
Primary Interest:
Prospecting
Re: Metal detector & pyrite...and eventually gold

It does pick up earthsmagnetic field, also, you can't hold samples in the palm of your hand because it will pick up the iron in your blood. I use my MD20 a couple of different ways. First, just like a regular probe with my Lobo Super Traq. It's not as handy as my vibraprobe as a belt stored probe, but I will not go into gold country without my MD20. The other way I use it is I plug in the optional headphones, and install the optional extender tubes on the probe, and walk up wet or dry stream beds and probe the cracks and crevasse's.






UncleVinnys said:
nuggetshooter323 said:
I have a Lobo Super Traq and it works at 17.5 khz, and it doesn't utter a peep with pyrite, which is just fine with me. Now I have a Falcon MD20 probe, and it works at 300 khz, and it also doesn't utter a peep with pyrite. Why does the GB2 sound off at 70 khz with pyrite?

Greetings . . . I just got the Falcon MD20 too, and was VERY IMPRESSED at its
super sensitivity. I tune it to just under oscillating, and I swear you can pick up
the earth's magnetic field by twirling that thing around !!! . . .
Anyway, I'm wondering how you use it, how it is used in conjunction with the
detector or by itself??
 

OP
OP
S

ssr60

Newbie
Nov 14, 2007
3
0
Re: Metal detector & pyrite...and eventually gold

Hello !

What to find a better iron pyrite (iron sulphide) PI or VLF metal detector ?

Thanks you everyone !
 

Jim Hemmingway

Hero Member
Jan 26, 2008
788
1,615
Canada
Detector(s) used
F-75, Infinium LS, MXT, GoldBug2, TDI Pro, 1280X Aquanaut, Garrett ProPointer
Primary Interest:
Prospecting
Re: Metal detector & pyrite...and eventually gold

Hi SSR60,

It's been a year since you last posted on this topic. I presume you have not purchased a suitable detector, and I think you should consider that option carefully. I don't know about PI's ability to find this type of target, as I have not tried one.

To place this subject into perspective, trying to detect a dollar size piece of iron pyrite is about equivalent to locating a gold nugget sized between one and two grains or so.

A VLF unit must be highly sensitive to very low conductives like iron pyrite. That means a nugget hunting designed unit, and the highest frequency would be best overall. A GoldbugII or GMT will give the best performance to sensing low conductives.

I have tested all three of my prospecting units that range in operating frequency between 13 and 15 kHz... on a dollar size chunk of pyrite in the air here (the ground is frozen). All three units will sound off at roughly3 1/2" to 4", with a "diggable" signal at 3" or less depending on the unit. That's with the ground balance set to an equivalent of about 80ish (to simulate decently higher mineral ground) on MXT for all units and using all-metal motion mode. Non-motion all-metal mode (if available on the unit) can get an inch or so more, depending on the unit.

Those are air tests, I doubt you'd get much more than half that in higher mineral ground. I suggest that if you are intent on using a metal detector to search for pyrite, borrow a suitable unit, or rent a unit and try it out first.

Here in Ontario, we have abandoned pyrite mines especially in the eastern townships. You can walk into areas where the ground literally glitters with pyrite particles and larger pieces are often located just below the surface by common rockhounding methods ie pick, shovel and screens. If your research indicates such opportunity exists in your area, I would recommend you try this approach prior to buying a detector. Good luck and HH,

Jim.
 

Yellow Hammer

Full Member
Nov 17, 2008
146
8
Anaheim Ca and Quartzsite Az
Detector(s) used
Minelab SD2200v2/GP4500
Re: Metal detector & pyrite...and eventually gold

Hey Jim,

About the PI detector and pyrite. I have never picked up pyrite on my coil and always hunt in all metal. One day while digging a nugget I did find a nice nugget of pyrite but it was not what set the coil off that would have been the 1/4 oz nugget. Even waving the pyrite nugget in front of the coil there was nothing. Hope this helps about using a PI.
 

Jim Hemmingway

Hero Member
Jan 26, 2008
788
1,615
Canada
Detector(s) used
F-75, Infinium LS, MXT, GoldBug2, TDI Pro, 1280X Aquanaut, Garrett ProPointer
Primary Interest:
Prospecting
Re: Metal detector & pyrite...and eventually gold

Thanks for adding your comments Yellow Hammer. I thought as much too.

You know, generally VLF units pretty much ignore pyrite unless set-up in a benchtest. I felt he should have that questionable information just to be complete, but I don't see metal detecting for pyrite as a good idea. My 2 cents worth is to stick with basic rockhounding tools...shovel, pick, screen and bucket.

I have an unusual question about PI units that you may have run across. I was in an area this past autumn that was littered with pyrrhotite. Its a low conductive iron sulfide that blocs VLF signals and makes some spots impossible to hunt. Do you have any idea if your PI unit will see through this stuff? Or does it respond with a signal? Take care,

Jim.
 

Yellow Hammer

Full Member
Nov 17, 2008
146
8
Anaheim Ca and Quartzsite Az
Detector(s) used
Minelab SD2200v2/GP4500
Re: Metal detector & pyrite...and eventually gold

Yes you will get an audio signal from the pyrrhotite but the PI will punch below it and the tone will be different and light. Even with the PI it will be frustrating as hell.
 

jimmydetector

Newbie
Jun 1, 2012
2
0
Primary Interest:
All Treasure Hunting
I bought a gold metal detector for gold not long ago and in order to test whether it is useful I have used it to find underground metal goods that hidden in my garden, to my surprise it has found my mother's lost golden ring. Then I took it to the park and the gold metal detector find a few coins. Really amazing and I want to share it with your guys.
 

jmoller99

Sr. Member
Jan 8, 2010
294
109
Colorado Springs, Colorado USA
Detector(s) used
Whites GMT, Goldmaster Vsat, 5900, Bounty Hunter Discovery 3300 and Falcon MD-20.
Primary Interest:
Other
Sulfides are next to impossible to detect for (I find a lot more trash with a detector than sulfide based ore). My Falcon MD-20 is of no value with it either. If you have the right pyrites (those that contain small free gold mixed in with the pyrites are somewhat detectable - I have some ore samples from the Phoenix Mine near Idaho Springs in Colorado that contains tiny flecks of gold along with chalcopyrite - the MD-20 will find those. but only from 1/4 of an inch away - even then you have to be right on top of the gold).

Finding a gold ring is an accomplishment, no matter what type of detector you have. My GMT is great at finding gold, but it would drive you crazy looking at a park for any coins/collectables - its not set up or designed for doing that at all. I do have other detectors that are more general purpose.

Pyrites can smell oniony/garlicy if freshly broken, but its a pretty faint smell even in a large sample.
 

Lanny in AB

Gold Member
Apr 2, 2003
5,651
6,341
Alberta
Detector(s) used
Various Minelabs(5000, 2100, X-Terra 705, Equinox 800, Gold Monster), Falcon MD20, Tesoro Sand Shark, Gold Bug Pro, Makro Gold Racer.
Primary Interest:
Prospecting
SSR60,

Wow--I hope you realize the caliber of the metal detecting heavyweights that have responded to your post! You've been getting input from some of the best of the best--listen carefully--they know what they're talking about.

All the best--I've really enjoyed reading this thread--

Lanny
 

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