Electronic Prospecting in Silver Country - Part 2

Jim Hemmingway

Hero Member
Jan 26, 2008
791
1,624
Canada
Detector(s) used
F-75, Infinium LS, MXT, GoldBug2, TDI Pro, 1280X Aquanaut, Garrett ProPointer
Primary Interest:
Prospecting
Electronic Prospecting in Silver Country - Part 2
ā€œA Discussion about Metal Detecting Silver Ores and Nuggetsā€

Introduction

This is the last of several articles about silver hunting that have been posted to the forum in recent years. While I hope everyone will see something interesting and enjoy the read, it is geared towards rockhounding enthusiasts involved with electronic prospecting for silver nuggets and ores. Many such people enjoy getting out for a day to prospect an abandoned minesite but that is about the extent of their participation within the hobby. What follows is designed to provide these hobbyists with some additional information about metal detecting and equipment selection specific to this application.

It has become more difficult to locate large multi-pound specimens that were somewhat commonplace years ago. But the silverfields continue to consistently supply good quantities of small silver to casual electronic prospectors despite searching easily accessible abandoned minesites. Some patience and physical effort is required to be successful, because many recoveries will be man-made ferrous and non-ferrous trash, and associated conductive minerals primarily in the form of sulfides and arsenides that respond to a metal detector.

Autumn is the preferred season to hunt for silver. The bugs are mostly gone and temperatures cool down such that we can comfortably search and dig targets. Autumn colors as depicted below are an additional benefit to what should be a non-competitive and relaxing experience.

AUTUMN ELECTRONIC PROSPECTING BEAVER LGRSF.JPG

As discussed briefly in last yearā€™s article entitled ā€œElectronic Prospecting in Silver Countryā€ http://www.treasurenet.com/forums/canada/282315-electronic-prospecting-silver-country.html weā€™ll take another look at utilizing the ā€œGROUNDGRAB / FASTGRABā€ ground balance feature available on many current prospecting-capable VLF units as an additional tool to help determine target ID. While there is more to do, further evaluation of the technique with an F75 was done in the field this past autumn and that information will be presented later.

Silver Ores and Nuggets

The small silver specimen depicted in the photo below exemplifies the quality and typical size of native silver nuggets and specimens commonly recovered in silver country at the present time. This particular piece was found using the F75 in the motion all-metal mode, near maximum sensitivity http://www.treasurenet.com/forums/c...5-metal-detector-revised-february-2011-a.html with a ground balance setting at GB86 and a typical Fe3O4 bar graph magnetic susceptibility readout at 0.3% EM. Thatā€™s a bit tougher ground than a ā€œmoderateā€ designation would indicate but certainly is nothing extreme.

4.7 OZT SILVER CALCITE SFBB16N.JPG

The strength of ground magnetic susceptibility should have little or no impact to oneā€™s target recovery technique because overburden should always be removed until a strong signal and reliable target ID readout can be obtained. If in any doubt at all then you must dig the target. Otherwise disregard target ID over any but shallow targets with good strong signals because in these soil minerals silver can read as iron. On the other hand compact iron and larger high conductive iron such as drill rods and implements can and usually do read as silver even at modest depths.

The native silver ores and nuggets found here share a similar conductive range to gold, but we encounter greater numbers of higher conductive silver right up to and including the silver dime category. The majority of silver ores tend to reside within a category from foil to pulltab range. Silver ores may contain very pure native silver or the silver may be associated with a number of minerals common to the area. Those normally encountered by electronic prospectors include safflorite, cobaltite, niccolite, and skutterudite. And there are other substances associated with silver ores, for example a wide variety of sulfides and iron oxides, that may or not be detectable in the field but nonetheless frequently co-inhabit the same rocks as detectable native silver.

The specimen depicted below approaches the upper limit to what is described here as small silver when referring specifically to silver specimens rather than to silver nuggets. A three or four pound specimen is nothing unusual in the silverfields and is certainly nothing to be terribly excited about unless itā€™s an attractive ā€˜specimen qualityā€™ piece.

3.8 LB AG CALCITE SFYG18LOG.JPG

Detector Selection


Which detector models are best suited for this application? I own several PI and VLF units to deal with variable field conditions and objectives. Field conditions refer to ferrous trash levels, the strength of ground mineral magnetic susceptibility, hotrock abundance, the physical site conditions and to the anticipated size and depth of the silver for which one intends to search.

For general scanning my usual preference is ground-balancing PI unitsā€¦ currently the Garrett Infinium and the Whiteā€™s TDI Proā€¦and reasonably large searchcoils to improve depth and coverage where field conditions permit their use. Otherwise smaller PI searchcoils are a mainstay because they are more versatile over high-density target areas and rough terrain. The motion all-metal modes on VLF units that offer target IDā€¦ used in concert with quality headphonesā€¦ perform well especially over more moderate magnetic susceptible iron minerals typical of many minesites here. Iā€™ve explained in considerable detail my PI preferences for silver hunting in past articles posted to the forum. These can be located at http://www.treasurenet.com/forums/c...ntry-infinium-comparison-february-2011-a.html and at http://www.treasurenet.com/forums/c...erfields-ontario-revised-february-2011-a.html

Letā€™s have a look at the handsome ā€œspecimen gradeā€ silver piece below, and then weā€™ll review some basic points to consider when selecting a ground-balancing PI unit for this application.

3.3 LB AG NUGGET SF18YGROR.JPG

The primary reason for PI usage is to improve depth over VLF units in tough magnetic ground minerals. If one cannot achieve sufficient depth with a VLF unit to acquire deeper silver signals then all other VLF features or capabilities are of no consequence. The PI units Iā€™ve selected also have a limited but very real ability to separate large and especially elongated iron from all silver ores and nuggets. The other main benefit of PI units is their ability to ignore most non-conductive iron mineralized hotrocks. However they do respond to conductive hotrocks such as the ever-present iron sulfide mineral pyrrhotite. Moreover, neither of these PI units can differentiate low conductive silver from low conductive ferrous trash. And that is precisely where the value of VLF target ID and discrimination features have an advantage over PI units in this area. At high trash sites PI operators can spend their days digging deep and shallow low conductive iron junk, and become frustrated with finding comparatively little or no silver.

But there are alternative search strategies with these units. One can flag PI target signals and recheck them with a VLF unitā€¦ thus eliminating the need to fully dig innumerable iron signals. Alternately, one can forget about using PI units in trashy areas and hunt exclusively with a VLF unit in the motion all-metal mode utilizing target ID effectively by removing overburden as described earlier. Another alternative in more severe trash areas is to search with a VLF unit employing a discrimination setting to eliminate most small iron signals. In such circumstances it is better to find some silver and avoid unnecessary digging and frustration dealing with countless blaring iron signals. In summary, itā€™s not difficult to understand why appropriate use of both PI and VLF units will improve our successful recovery of silver.

After viewing the attractive dendritic silver specimen below, weā€™ll discuss how the TDI Pro and Garrett Infinium are used for this application. The dendritic silver structure was not apparent in the fieldā€¦ in fact there was very little silver showing on the surface. Acid baths frequently expose native silver structure that surpasses our hopes or expectations as occurred in this instanceā€¦ one of my favorites.

3.2 LB DENDRITIC AG CALCITE SF18YGLOGS.JPG


Review of the Infinium and TDI Pro for this Application

I tend to use the TDI Pro for specific tasks in this application, for example in high nail-infested areas, operating in the low conductive tone mode to capture low conductive silver ores while eliminating many of the nail signals. And silver ores are predominately low conductives. Silver hunting is a different ballgame from gold hunting insofar as silver normally comes in much larger sizes, and signals may be quite similar to larger ironā€¦these are easily confusedā€¦ particularly at depth. Compact large iron signals are very difficult to distinguish from silver ore signals, whereas as noted aboveā€¦ either unit is capable of identifying large elongated iron including larger nails at reasonably good depth.

The Infinium with its automated tones is quick and effective at differentiating elongated iron including nails from silver ores, and in zero discrimination will indicate compact iron such as drillbits, larger milling balls and other nondescript ā€˜chunkyā€™ iron with a lo-hi tone. Only silver with conductivity at or above fringe zinc penny level will respond similarly and they are an infrequent occurrence. So we have a solid indication that the target is most likely iron and we can choose to ignore it at the risk of ignoring infrequently encountered high conductive silver. We can play the odds and those odds are very much in our favor. Alternatelyā€¦we can check that target signal in reverse discrimination. If the signal changes to a hi-lo signal and particularly if the signal volume undergoes a serious reductionā€¦ we should dig it to avoid the possibility of losing any silver. Itā€™s your choice based on useful indicative information. Most compact iron as described will change over to a hi-lo signal in reverse discrimination too, but it tends to retain most of its signal volumeā€¦ and such iron is mostly what we encounter digging those signals.

5.4 LB AG CALCITE SF18YGNAT.JPG

By comparison the TDI Pro is not effective at indicating the identity of compact iron. With time-consuming GB control adjustments we can occasionally obtain a weak lo-hi-lo definitive iron tone in the all-conductive tone mode, but mostly that is not the case and we have to dig such signals. By and large itā€™s a waste of time and energy. Secondlyā€¦in the low conductive tone mode and properly ground-balanced the TDI Pro will ignore most nails but it does occasionally signal over larger elongated iron such as rail spikes and drillrods with either a good positive signal or a rather spurious signalā€¦in part depending on the coil sweep direction. Now these can normally be identified with a lo-hi-lo tone and often without adjusting the GB control. But it means setting aside your pick, flipping the toggle into the all-conductive tone mode and sometimes adjusting the GB control to recheck such signals. Not a big deal but it takes additional time to manually check such signals and that time adds up over the course of each day.

The result of the above is that more ground can be covered with the Infiniumā€™s automated tones and more effectively because some unnecessary digging in tough rocky substrates is avoided. So for general searching my preference is the Infinium. For this application I prefer to use the TDI Pro as a ā€œnicheā€ unit as described above. The Proā€™s ability to eliminate signals from either high or low conductives permits searching trashy areas that otherwise would be difficult or impossible to properly search with the Infinium. The Pro is equipped with either my 10ā€ elliptical mono or 5 Ā¼ā€ round mono for this workā€¦ and combined with a very slow sweep speed really improve target separation over trashy ground while acquiring the best depth possible for those coils.

The photo below depicts what turned out to be a handsome ā€œnuggetyā€ silver specimen. It should have been field-cleaned prior to a photoā€¦ but nonetheless you can see the silver horns poking out beyond the dirt. Following the photo weā€™ll conclude this discussion with an illustrated side-by-side depth and sensitivity comparison of these units over freshly buried targets.

1.7 TROY OZ HIGHGRADE SILVER.JPG

Operated at bare thresholds the TDI Pro is a noticeably deeperseeking and more sensitive unit. The Infiniumā€™s depth / sens is improved by adjusting the threshold control up to 6ish or slightly more and adjusting headphone volume to preference. With this adjustment to Infiniumā€¦I see little or no difference between these units regarding depth / sensitivity over a variety of targets buried at variable depths in my testplot. There is some variability between different types and sizes of coils of courseā€¦we see that large coils tend to be deeperseeking on larger targets and less sensitive to shallower small stuff and vice-versa for small coils. Mono coils are deeperseeking compared to similar size DD coils in this moderately tough ground. Infiniumā€™s mono coils are more likely to signal over high conductive large iron with an iron indicative lo-hi tone.

Now letā€™s look at some low conductive target responses presented in the chart below. As noted above, the majority of silver ores are low conductive. Keep in mind these depths do not represent the full capability of these units. Using solid lead ā€œnuggetsā€ instead of gold or silver nuggets, the fact that theyā€™re freshly buried, and rather severe local EMI conditionsā€¦ all contrive to reduce detection depth compared to silver nuggets in the field. But they do work just fine for relative side-by-side depth comparisons between these units. For this comparison, Infinium threshold is set to slightly above ā€œ6ā€ at zero discrimination, with the GB locked. The TDI Pro is set to proper ground balance at GB9, maximum gain when possible, and a bare threshold. The chart designations indicate Weak, Fair, and Good signal responses.

I tend to compare the 8ā€ Infinium round mono to the TDI designed Razorback 5 X 10ā€ elliptical mono, and the Infinium 10ā€ X 14ā€ elliptical mono to the TDI Pro 12ā€ DF round stock coil because these are comparable sizes. I think we can agree that the results are fairly closeā€¦the variances are likely due to the coils tested. While I see no significant advantage either way on these low conductive targets, the Infinium 8ā€ round mono searchcoil performs best overall.

TDI PRO - INFINIUM GROUND DEPTH COMPARISON (1).JPG


Review of VLF Units for this Application

Natural silver occurs in a comparatively large size, and in a wide conductive rangeā€¦ although the majority of silver is low conductive. It seems to me that VLF units operating in the mid-frequency range, such as MXT at 14 kHz or F75 at 13 kHz, are a good overall compromise. Lower operating frequencies also work for this application but may be slightly less sensitive to fringe depth low conductives. With the objective of coin-size and larger silver, I doubt itā€™s a terribly significant issue. But years of digging low conductive silver have sufficiently impressed me with mid-frequency unitsā€¦ particularly the F75ā€¦ that these are my preference.

Mid-frequency range units are sensitive to both high and low conductors, and respond well to weaker signals produced by low conductive disseminated and sponge silver. Compared to high frequency units (a) they are less vulnerable to elevated magnetic susceptible ground minerals (b) see both higher conductive targets and larger targets at better depths and (c) have the advantage in this application of slightly less sensitivity to tiny bits and pieces. Keep in mind that silver is not gold, and we do not want to be distracted by tiny target signals.

There are many suitable mid-frequency VLF units currently available with variable feature sets. I donā€™t presume to advise anyone which model to purchase. Experience has shown me that any number of these units will perform well in the silverfields if operated competently. My preference includes features such as target ID in a threshold-based motion all-metal mode, a discrimination mode, a manually adjustable visually calibrated full range ground balance, a ā€œfastgrabā€ ground balance for its convenience and to assist with target signal evaluation, and a decent selection of searchcoil types and sizesā€¦ all in a reasonably lightweight, well-balanced package.

The photo below is a small native silver nugget found a few years ago in mine tailings while using the F75. Itā€™s a favorite find for nostalgic reasons, and serves a useful purpose here. It was the piece that firmly settled me into a comfort zone with the F75. At that time I viewed this unit as a questionable choice for this application. It had put me off in town with its invariable chattering in response to EMI when operated in discrimination modes at higher sensitivity settings. But I quickly learned that in remote prospecting environs it ran as quiet as a churchmouse at similar settings in any operating mode. And thereā€™s nothing like finding a snootful of silver at good depth to form a long-term bond with a new unit.

3.7 OZT SILVER NUGGET SFPANYGG19.JPG

VLF Searchcoil Selection, Type, and Size

Stock coil size on most units is normally quite sufficient for this application, but it doesnā€™t hurt to have a small ā€œshooterā€ coil handy for tougher mineral ground, sites with abundant trash, and to facilitate searching jumbled tailings where coil maneuverability is an asset. Large coils are fine for lower trash density areas where ground minerals are not too harsh. Once popular with hobbyists for covering ground and ā€˜cherry-pickingā€™ shallow silver, theyā€™re infrequently seen these days. With target ID meters now available for the all-metal modes on many modern prospecting-capable detectors, most hunters seem content to go that route utilizing stock coils. Theyā€™re a good compromise in trashy tailings, handle ground minerals better than large coils, and have good depth and sensitivity to small and large silver.

Incidentally, pinpointers are highly effective in this application where all too frequently multiple signals exist in our diggings. My rugged Garrett Propointer is a real timesaver. Although I usually remember to keep my thumb over the speaker at such moments, it has been completely immersed in water countless times, has withstood repetitive severe digging abuse, and yet it still works just fine. And one nine-volt rechargeable battery lasted for an entire two-month seasonā€¦the Propointer is a gem.

The photo below depicts another typical example of a small ā€œspecimen gradeā€ silver ore found with the F75 at a popular collecting site readily accessible by car. Despite the lack of clarity in the photo, those darker areas represent silver at or just below the surface. You might think the large silver vein would increase the target ID conductivity, but I doubt the EMF even sees most of it due to ā€œblockingā€ from adjacent ā€œparticulateā€ native silver structure.

1.2 LB VEIN-DISSEMNIATE SILVER CALCITE.JPG

When selecting a VLF searchcoil suitable for this application, the main factors to consider are iron trash abundance, the physical site conditions, and ground mineral magnetic susceptibility. We canā€™t change the search conditions so we must adapt our equipment and search technique to them. For example, you may plan to use a larger searchcoil to improve ground coverage and gain some additional detection depth. But nyet comrade, you find youā€™re unable to consistently keep the coil to its ground-balanced elevation over the ground due to surface irregularities, for example jumbled tailings. It results in distracting spurious ground signals. Unfortunately large coils see more ground mineral and react accordingly. You are faced with significant gain reductions to be able to continue searching with an unsuitably large coil. Alternately you may find that you are located at a high target density site where large coils are a poor choice. Signal evaluation is not possible when there are multiple targets under the coil. In either case a smaller searchcoil is warranted by site conditions that do not accommodate a large coil.

To reiterate, your best bet in most areas is to stick with the stock searchcoil and only make changes if the search conditions warrant or accommodate doing so. Ground coverage used to be a key strategy years ago when shallow quality silver was plentiful, but that is no longer the case at sites that have seen decades of collecting pressure. Electronic prospectors are well advised to take their time when searchingā€¦ slow down and find more silver over the long haul. This strategy will enable you to hear and investigate very faint signals that are certain to net occasional multi-lb specimens at depth similar to the one below.

1.9 LB DENDRITIC AG CALCITE SF17YGBLACK.JPG

In summaryā€¦ larger searchcoils cover more ground and are modestly deeperseeking on larger targets in moderate to light magnetic susceptible ground minerals. They lose sensitivity to small targets, and are more reactive to ground mineral effect. Small searchcoils cover less ground but are easier to stickhandle around rocks and bushes and maneuver into tight spaces, and are much lighter on the armā€¦ a real benefit if hunting daily. They improve sensitivity to small silver and help with pinpointing what are normally hard-to-see targets covered in dirt. And yet even the small ā€œshooterā€ coils have surprising depth for their size, while significantly reducing interference from ground minerals and dramatically reducing EMI. The smaller coils have plenty of attributes to recommend them even for this prospecting application.

Ground minerals do not affect DD searchcoils as much as same size and shape concentric searchcoils because DDs see significantly less ground, and this is visually evident in reduced GB and Fe3O4 readouts. A result is that at some level of magnetic susceptible ground mineral strength, DD searchcoils will surpass same size and shape concentric coils depthwise. But that rule doesnā€™t seem to apply to shooter coils. I see little difference between my 5ā€ round DD and 6ā€ elliptical concentric coil over any ground. In fact the 6ā€ elliptical seems slightly more sensitive to buried small stuffā€¦ interesting for gold huntingā€¦ but not important here. Other DD benefits include wider sweep coverage and improved target separation compared to same size and shape concentricsā€¦ but they are more susceptible to EMI.

Despite the foregoingā€¦ my F75ā€™s 10ā€ elliptical concentric is normally my preference here. Itā€™s considerably smaller, lighter and more maneuverable than the stock 11ā€ DD coil, and any minor depth loss incurred usually takes a backseat to its attributes. It is more sensitive than the stock 11ā€ DD in the all-metal motion mode, is more adept at target signal evaluation, and is a more reliable iron discriminator. Target signal evaluation is the one aspect of this application that warrants study, because there is a widespread proliferation of ferrous and non-ferrous trash, non-conductive and conductive hotrocks, and various minerals usually in the form of arsenides and sulfides that react to a metal detector. In some areas these can at times be overwhelming.

With that in mind, have a look at the high conductive silver specimen below, and then weā€™ll present some results from this past autumn using the GROUNDGRAB / FASTGRAB feature found on many modern prospecting-capable VLF units to assist with target signal evaluation.

1.9 LB AG CALCITE ROCK SF18YGZINC.JPG


FASTGRAB / GROUNDGRAB for Target Signal Evaluation

Last yearā€™s article ā€œElectronic Prospecting in Silver Countryā€ introduced this subject with the comment that the GROUNDGRAB is accurate and convenient, and is an additional quick source of information when evaluating questionable signals. It makes searching hotrock areas properly ground-balanced in the all-metal motion mode more feasible because it takes only a moment to check out a suspect hotrock signal and then quickly re-balance to the ground and continue searching.

It was further noted that our positive diabase hotrocks read consistently in the upper iron range at target ID ā€œ14ā€ on the F75. But when ground-balanced using the GROUNDGRAB / FASTGRAB technique they lose their positive signal, their target ID disappears, and there is always a small reduction in the ground balance readout. Other positive non-conductive iron-mineralized hotrock types in this area react similarly but experience more variable GB reductions.

Some preliminary observations were also reported on variable silver ore responses, reduced GB readouts on ferrous junk, and niccoliteā€¦ a nickel arsenide. We confirmed this year that as anticipatedā€¦ the technique is not definitive for many targets encountered in the field. But we did learn more about what can be expected and readers may find the results interesting.

Keep in mind these results were obtained using an F75 operated in the motion all-metal mode. Note that the F75ā€™s FASTGRAB feature does not permit ground-balancing below GB40. This feature prevents the unit from tracking completely into metals. The manual ground balance must be used to compensate for ground with GB values more conductive than a GB40 setting.

4.9 OZT LEAF SILVER SFPAN18YGXD.JPG

The FASTGRAB / GROUNDGRAB technique is subject to a few conditions. (a) It applies only to targets buried in undisturbed ground. Other than non-conductive hotrocks it does not provide meaningful test results if done over targets placed on the groundā€™s surface. (b) The target must be accurately pinpointed prior to a fastgrab exactly over the pinpointed target signal. The issue is that all too often the subsurface is littered with all kinds of metallic debris and mineralized rock both large and small. These can play havoc with any attempt to acquire unequivocal fastgrab results, as do iron mineralized ā€œhotspotsā€ remaining from rusted and disseminated bits of iron. (c) Do not try and ā€œbrute forceā€ the fastgrab by repeatedly pumping the coil over a target. It only takes three or four pumps to acquire accurate ground balance over clean ground, so we never exceed five pumps over a target. The concept is to permit the unit to make the decision about whether or not it will track into a target and by how much. (d) Itā€™s not a condition but I do prefer the F75ā€™s 10ā€ elliptical concentric to the stock 11ā€ DD coil for this work. It seems better able to retain the positive portion of a signal as you sweep a ā€œfastgrabbedā€ conductive ore or metal target that the DD tends to want to attenuate into more of a negative hotrock ā€œboingā€ or ā€œtwangyā€ type signal. Itā€™s not a big deal and in some cases you hear little or no difference between coil types. But experience tells me the concentric coil is more consistent in preserving a positive signal over conductive targets.

The first photo is self-explanatory. Low-grade conductive pyrrhotite tends to reduce the ground balance readout variably from the GB40s well into the less conductive GB70s. These weak strength conductive hotrocks sometimes lose their signal similar to non-conductive positive hotrocks. More typical higher-grade pyrrhotite keeps its signal but the ground balance readout almost invariably drops into the GB40s as illustrated in the photo.

FINAL MERGE FRAMED.JPG

Much of the rusted iron junk dropped the ground balance into the GB40s. The large rusty nail results below are typical. Smaller bits and pieces of nails or whatever were more variable and could read higher on the GB scale. The questionable iron targets were large iron such as drill bits and rods or implements. If these were shallow strong signals, the unit would not usually track into them. There was no choice but to dig these signals after removing overburden if they consistently read above the iron target ID range.

On the same items but deeperā€¦ the unit was much more likely to track into them yielding similar GB results to those in the photo below. But as a rule of thumb, rusty iron responded to the fastgrab with sharply reduced ground balance readouts. A good many of these dropped into the GB40s and they retained their positive signals.

2ND FINAL MERGE FRAMED.JPG

Most pristine silverā€¦ that is to say silver ores without any visually obvious associated cobalt or niccolite mineralsā€¦ did not track downwards more than seven or eight points over most of the two month trip. In fact most of it remained virtually unchanged as illustrated with the silver in the photo below. But near the end of the trip several silver ores were recovered at one site that looked free of other minerals, yet the fastgrab GB dropped by twenty points to the mid-GB60s. Checking the holes didnā€™t reveal any obvious mineral staining or other material that might account for this result.

Other items, for example blasting caps, yield variable responses to the fastgrab technique. Occasionally the GB doesnā€™t react at all, but most blasting caps produce a steep ground balance reduction to the GB50 range and retain a positive signal. Cobalt and niccolite ores can react with sharp GB reductions but retain a positive signal. It seems to me that cobalt signals were more likely to produce GB reductions into the low GB40s. The signals from silver, iron junk, and other conductive ores are weakened to some extent when subjected to the FASTGRAB / GROUNDGRAB techniqueā€¦ some more than others. But regardless, all strictly silver signals checked this season retained a good positive signal.

In summary, this technique is an effective tool to distinguish non-conductive positive hotrocks from metal targets and most conductive ores because non-conductive positive hotrocks lose their signals and target ID. GB reductions are not consistent with all iron types and sizes, with all silver ores, or with other man-made trash such as blasting caps. Cobalt and niccolite dominant ores tend to overlap the iron GB reduction range. A result is that operators could ignore mixed ore samples that may or not contain some silverā€¦ if they rely exclusively on this technique for target signal evaluation.

More ore samples need to be checked at a wider variety of sites to be more definite about the results to date, but those results indicate strictly native silver samples do not groundgrab / fastgrab into the GB40s. Ground balance reductions into the GB40s have overwhelmingly been undesirable targets that are mostly iron trash. For example, dimes to doughnuts says that a target ID reading in the screwcap conductive range that experiences a GB40s fastgrab reduction is almost certain to be round or chunky or otherwise larger rusty iron.

3RD FINAL MERGE FRAMED.JPG


Closing Remarks

Letā€™s conclude this write-up with an appreciative word about a new friend, Sheldon Ward. We became well acquainted while doing several hunts in the bush. As can be seen above, Sheldon generously put aside his own pursuits to volunteer his help with the ā€œfastgrab projectā€. He is an accomplished silver hunter as evidenced by his knowledge and many beautiful silver finds.

The photo below depicts him with a 153 lb highgrade silver ore that he found recently with an F75 metal detector at a couple of feet depth. It has an impressive showing of native silver, reads at silver dime conductivityā€¦thatā€™s the maximum hereā€¦ and is certainly museum quality.

SHELDON 153 LB HIGHGRADE SILVER (B).JPG

Thatā€™s itā€¦ thanks to everyone for spending some time here. Comments are welcome. For newcomers to the hobbyā€¦ no question is awkward or foolishā€¦ so donā€™t hesitate to ask it.

Jim Hemmingway
January 5, 2013
 

Last edited:
Upvote 0
Better here than the Canada Forum. I think more of it as metal detecting for precious metals, not gold only. Great write up!

Steve Herschbach
 

As always, fantastic write-up Jim--tons of time invested in your writing and gathering and displaying your pictures as well. Thanks for your dedication.

All the best,

Lanny
 

Wow Jim, what a wealth of information and it continues right along with the finding of any precious metal......63bkpkr
 

Hi Daveā€¦ you may have noticed a few embellishments such as a new photo or twoā€¦ but otherwise the essay text is essentially unchanged. Thankyou for taking a moment to comment here.

I doubt there has ever been a time when contemplating the electronic prospecting capability of my F75 that I havenā€™t thought about your many contributions to the metal detecting / prospecting community with genuine appreciation. The times Iā€™ve asked you to look something over, or needed some technical adviceā€¦ youā€™ve always responded promptly and on your personal time.

Here is an opportunity to openly acknowledge that help and thank you for all your contributions to the hobby over the years. :)

Jim.
 

Hi Steveā€¦ trust you to put things into a sensible perspective. :)

I recollect Reg made a similar comment last year, and that decided me to post here. Thanks for your commentsā€¦ thereā€™s no question that this should be the place to discuss any electronic prospecting application, and certainly nobody has ever said otherwise thank goodness.

Jim.
 

Thanks Lannyā€¦ most kind coming from a gifted writer disguised as a gold-seeking bushwhacker from Alberta. :)

I finally learned how to take decent digital specimen photos that might be worth passing along. Instead of fiddling around with manual exposure and focus controls as per the old SLR film camera days, I put the wifeā€™s digital camera on automatic and took the shots on a cloudy day. The result? Almost perfect exposure between the silver and light-hued calcite. Although itā€™ll never reproduce the luster of native silver, these were marked improvements over past attempts using manual settings.

Jim.
 

Hi Herbā€¦ it sounds as if you enjoyed the essayā€¦ so Iā€™m pleased. Thanks for taking a moment to post your thoughts. :)

Sayā€¦ how are you enjoying that not-so-new job? Are you getting some decent vacation time to get out and do things, or are you just about ready to chuck it and head into the wilds for gold?

Jim.
 

Well Jim actually I'm about ready to go in for some surgery on the right shoulder. Completely torn Rotary Cuff and withdrawn into the lower arm, possible partial tear in another ligament, possible cartilage/bone damage. As you can tell all the info is not in, next MRI with Contrast should do it and then hopefully the surgery will be late Jan or early Feb. I would like it to be sooner rather than later as it is delicate now and could be damaged more while waiting/working. All in all the 2013 prospecting year is looking sketchy and just as I had to good spots to work at with another two maybe's in mind. Shucks.........63bkpkr
 

Herb... I am sorry to learn about your shoulder. My brother had something that sounded similar, maybe not quite the same... but yah... I think it was called "rotor" or "rotator cuff" surgery. He did come north prospecting not long after and stayed with me for a few weeks to make things easier. And harder for me... that fool snores... I couldn't get any sleep until finally in desperation I put on my Nugget Buster headphones for some peace and quiet. He didn't have to lug any equipment around in the bush like you do, just detecting with his good arm, laying the unit aside to dig and retrieve.

Each morning and again after dark, I'd help him with his exercise program of lifting a bar overhead, correct posture etc, and hold the bar for a count of 10. Lower it and then repeat 10 times. The physiotherapist was pleased with his progress and the following summer he was good to go... no issues.

So maybe you'll be able to get out next summer for some light detecting excursions, but no extended trip... and certainly no lugging extra equipment. I've often thought about hiring students to do my hard extensive digging for a few days... no... I guess that wouldn't really work for your deep bush destinations inaccessible by vehicle.

Jim.
 

Jim,
Thank you for the input on your brother's surgery/rehab/outcome, I expect the same thing for me. You are correct, where I go no land vehicle would be able to get there and in some places not even a helio unless the passenger came down a rope and braved the static charge. I fully intend to and will get back out there and I'm very excited about it!! Like a little kid with a brand new toy just waiting for him to go play!! One of these days I might just get myself a puppy dog to train up to go with me but I will have to teach it to be snake wise and to stay away from them!

Right now I'm preparing to "coil up" with the smallest DD coil White's offers for my XLT and I will finally have every coil they offer for it. Once it comes in I will detect around town and as you indicated the old one handed style for awhile, lucky I have wireless headphones.

Okay, dinner is calling! Thanks for the reply, Herb
 

Herbā€¦ just a word about your XLT. Iā€™ve used both the Whiteā€™s Eagle Spectrum and subsequently the Spectrum XLT extensively for coin hunting over many years at old ball diamonds, picnic groves, school yards, and of course local parks. Theyā€™re a lot of fun to use and I enjoyed good success with them both. If memory serves, theyā€™re 4-filter units and they do well over fairly tough ground minerals here. They were hot on high conductives, and discriminationā€¦ particularly the Signagraph for identifying ironā€¦ is excellent.

In fact for years Iā€™d snap one on my prospecting backpack specifically as a back-up unit to identify large iron such as commonplace drill rods at depth. Despite that occasionally large iron might give a ā€œgoodā€ audio signal, the Signagraph would consistently identify it. Iā€™ve always hoped that the Signagraph or something similar would be featured on one or more modern prospecting-capable units. That old Spectrum XLT is one unit I will never retire because of that capability.

Below is a smattering of tokens and coins similar to many found over the years with those units. Nothing smaller than quarters is included because they might be hard to see in this group photo. What you can't see is all the great memories while out coin hunting. Good luck Herb with your XLT and have lots of fun. :icon_thumleft:

Jim.
TOKENS & COINS SAMPLE.JPG
 

Howdy Takodaā€¦ thanks for taking a moment to drop around and comment. We have a lot of really good hunters in the areaā€¦ I could name a dozen sharpshooters without having to think about it. Nopeā€¦ Iā€™m just an old fool that took early retirement and started writing about it to stay busy in the winter. Discovered the existence of forums at about the same time and couldnā€™t resist being a nuisance. It hasnā€™t worked out too badly because Iā€™ve met a lot of wonderful people here and elsewhere. Appreciate the thought behind the comment though. :)

I also collect old bottles, itā€™s not a passion or anythingā€¦ but yah... Iā€™m definitely interested and have quite a number on display here at home. Below is the first bottle Iā€™ve never had to find or dig in the backwoods and it came to me this past autumn. Mind you it was terribly coated in layers of hard crusty grunge on the inside. But voila... after doing my bi-monthly wash of socks and other sundry garments... part of the remaining grey washwater was poured into the bottle and it sat just a few hours. Once emptied and rinsed this is the way it looked... no brushing required... :thumbsup:

Jim.
ANTIQUE BOTTLE.JPG
 

Last edited:
Hi Labusesezā€¦ thatā€™s an interesting bit of background to your pursuit, and of course we wish you all the very best with a successful conclusion to it.

Could I suggest to you that perhaps your query might attract more attention if posted to another section of the forum? Possibly the sub-forum Cache Hunting or alternately the sub-forum X Marks The Spot! might prove to be a more suitable choice.

Jim.
 

Jim this is a fantastic report. Your information will be valuable to the silver hunters in the area. I will try to get over that way next summer and see how my MXT will do. Can you suggest how it should be set-up? Regards, Bill.
 

great write up Jim. Very good read . Glad you are still at it . Very informative post , a lot of this info will carry over to other brands as well . And your attention to detail is remarkable. I need to get the ole gold bug out and apply some of these tips myself . great post !
 

Hi Billā€¦ thanks for your comments. Do you happen to belong to any of the local mineral clubs, and can you recommend a local forum that primarily focuses on prospecting?

In most areas my preference is to use the MXTā€™s prospecting all-metal motion mode for best depth and target signal evaluation. This mode allows you to monitor the ground balance readout when autotracking, and as you know it provides information about targets via the VDI #s, iron probability readouts, and the iron audio grunt. In high trash density areas I prefer to switch over to the C&J discrimination mode with a disc setting of about ā€œ2ā€ to eliminate most signals from small iron tidbitsā€¦ small nails, tacks, iron wire etc. In such areas I dislike using the relic mode options because I donā€™t want to hear the all-metal signals. Call it a personal preference, as I find the C&J mode easier listening in excessively trashy areas. Many prefer one of the relic mode options at least for general searching. In any case using a discriminate mode will result in occasionally missing good silver, but that is the price for the convenience of not digging a lot of blaring iron signals.

Autotracking can be used over tailings by and large, but in some areas littered with subsurface ironā€¦ whether oxidized hotspots or rusted metallic formā€¦ autotracking can lead to instability and false signals. The unit will attempt to track into such iron and this causes the problem. I prefer to ground balance the unit and search in the ā€œlockā€ position. This eliminates any potential for instability due to tracking into subsurface iron. It becomes second nature to pump the coil frequently to ensure the unit remains properly ground-balanced. When it becomes necessary to redo the ground balance sequence, simply flip the toggle over to ā€œgroundā€ and pump the coil a few timesā€¦ then flip it back into the ā€œlockā€ position.

Until you become familiar with your MXT over unfamiliar ground you should adjust the SAT control to the preset (white triangle). Depth reduction is minimal and it produces a crisp signal. Sweep the coil over clean ground and adjust the gain clockwise until the unit audibly becomes unstable and then back it off until it is stable. A stable gain setting produces more reliable target ID and is easier to interpret signals. With experience, you may prefer to increase the gain slightly into the ā€œbackground noiseā€ to improve depth.

Donā€™t rely too much on iron tones or iron readouts on anything other than strong shallow signals. Deeper silver may read as iron, and larger ironā€¦especially compact ironā€¦ usually reads as non-ferrous. Form the habit of removing material from suspect signals and recheck them. Incidentally, you might want to acquire an Eclipse 10ā€ DD elliptical coil for working rocks and brush or in trashy area.

Takodaā€¦ I see youā€™ve put up a photo of a spectacular gold in quartz specimen!!! I have no doubt that a lot of hard work and perseverance preceded making that find. Congratulations. :thumbsup:

The photo below depicts a mineral that I would dearly love to find in quantity or in association with native silver. Others recovered this specimen from a well-known minesite in the area. I did manage to find some very tiny proustite crystals in conjunction with native silver this year, but they are not large enough to photo with my equipment.

Jim.
PROUSTITE KEELEY MINE (S).JPG
 

Hi Strickmanā€¦ thanks Jim for taking a moment to comment. Hope all is well with you and the family, and that you enjoyed a good prospecting season. :)

Of course the above article is directed at silver hunters across the Great Lakes area, and is not likely to terribly interest those pursuing other hobby applications. It mainly addresses a few remaining topics not covered in my previous articles. The overall intent was to present a more realistic perspective as to what can be expected by everyday hobbyists in Ontarioā€™s silverfields. Last yearā€™s article, as you know, displayed some rare museum quality large silver specimens. Photos of such silver are powerful influences that may inadvertently lead some viewers to unrealistic expectationsā€¦ despite accompanying text that says otherwise. Hopefully the above write-up will help to correct any misconceptions in that regard.

One thing worth mentioning Jim is the TDI Pro. Again this year I was left with an impression that this unit is considerably more capable over undisturbed ground targets in the field than air tests or disturbed ground test plot evaluations indicate. I occasionally found small silver with good easy-to-hear signals that I doubt would have signaled in my testplot back home.

Below is my campsite just a few days prior to packing-up and leaving the area in early Novemberā€¦ in yet another swirling snowstorm.

Jim.
WINTER STORM (BB).JPG
 

Top Member Reactions

Users who are viewing this thread

Back
Top