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How about useable detectors for very high mineralization, pea gravel, rocks and IMB's?

September 26, 2020 12:16PM avatar
I figured I'd dedicate some time this morning to getting out of the grassy park and checking out performance in higher mineralization and dealing with IMB's. It was a pleasant fall-weather morning after a long-absent rain shower last night, and that sure made it feel fresh and pleasant to start the day.

I guess this would be the time to explain what an 'IMB' is to those who haven't followed my posts for several years. I used the term 'IMB' to describe an Intense Mineral Body, and that differs from ordinary dirt or other loose material that makes up a site. Through eons of time the mountainous make-up of rocks and material have eroded or been pulverized from erosion, etc., and that has resulted in the looser material that makes up the 'ground' or 'dirt' or 'surface material' in many of the places we like to hunt.

That material would be loose fine dirt or a dense make-up of dirt or material that you could 'toe-scuff. Because it is looser as searched, it is much easier for the detector's EMF to penetrate it, and also much easier for the motion-based Discriminate mode to handle the effects of that mineralization (looser make-up) on the EMF. Some detector circuitry designs struggle when trying to handle more challenging ground environments, and it can be caused by a GB issue, or by the Discriminate circuitry not being able to handle the environment and process out the ground mineral signal and pass along a target signal due to a too-high Discrimination setting.

When the mineralization encountered is NOT very loose or porous-like, that's when the detector's ability to deal with it really struggles. And there are three or four very dense mineralization challenges that we might encounter that comprise an IMB. Those would be, from a mildest to a worst challenge:

** A dense pocket of Black Sand, such as used in some playgrounds, but especially in places like a volleyball court.

** Pea Gravel, such as used in many urban playgrounds or other ground-cover use.

** A rock-covered area, such as a parking lot. Places with larger rocks that range from ½" to 2" in diameter.

** A single, bigger-size rock like some flatter rocks that stack easier for a chimney or structure.

The latter IMB is one that I used to encounter quite often when searching old dwellings that had decayed and were fallen-down, leaving a lot of those flattish chimney or building wall rocks scattered about a site. For several years I had what I called my 'Homestead Rock' that was from a Central Oregon homestead and it measured 6½"X9"X2" thick at the center.

What I looked for in a detector was one that could be used in the silent-search motion Discriminate mode and give a gig-worthy 'hit' on a US 1¢ coin that was under the rock It might be a ferrous or non-ferrous target, but I wanted to hear a 'Beep!' from any target UNDER the rock. Then, at a site with a lot of scattered rocks from a fallen-down structure, I would only have to move the one specific rock and then re-sweep w/o the interfering IMB and listed for the audio response and check the visual VDI for that target.


I'll head back out detecting later today and work some places with a more intense rock make-up as I mainly concentrated on some pea gravel locations this morning. Often many of the 2-Filter type detectors struggle to handle any of the IMB types of encounters with anything more than a very slow sweep speed. They just can't process out the ground signal when swept too fast. A lot of them still struggle even when using their lowest Discrimination setting.

I know a lot of those types of areas were a challenge for most slow-motion detectors with a quick-response and fast-recovery back in the '90s, and while some models could be adjusted to handle some tough site challenges, the White's MXT brought us some marked improvement. The reason was the use of their new 3-Filter circuitry design that has been a benefit to the MXT 'series' of models.

Lunch is over and I'm heading back out for more evaluation work with several makes and models. I'll report back later on how my current Daily Use Outfit is doing. This morning I was only using the Garrett Apex, but more will be employed this afternoon.

Have you been evaluating your detectors in some bad-ground environments? It can be quite educational.

Monte

"Your EYES ... the only 100% accurate form of Discrimination!"

Stinkwater Wells Trading Post
Metal Detector Evaluations and Product Reviews
monte@ahrps.org ... or ... monte@stinkwaterwells.com
503-481-8147
Detectors: Fisher F5; Garrett Apex; Minelab Vanquish 540; Nokta / Makro FORS CoRe, FORS Relic & Simplex +;
Teknetics T2+; Tesoro Bandido II µMAX & Silver Sabre µMAX; White's XLT
Pinpointers: Pulse-Dive -- ProPointer AT .. Headphones: 'Hornet' & 'Wasp' -- MS-3 Z-Lynk -- ML-80 -- N/M Green Edition
Note: Detectors are listed alphabetically by Brand. Models are chosen based on search site conditions.
*** All working well today to make memories for tomorrow. ***




Edited 2 time(s). Last edit at 09/27/2020 10:06PM by Monte.
Subject Author Views Posted

How about useable detectors for very high mineralization, pea gravel, rocks and IMB's?

Monte 110 September 26, 2020 12:16PM

Saturday was interesting with 7 different detectors.

Monte 70 September 27, 2020 08:35AM

The Results →→→ 7 detectors take on a 3"X4"X1¼" rock.

Monte 71 September 27, 2020 08:23PM

Re: The Results →→→ 7 detectors take on a 3"X4"X1¼" rock.

EL NINO 47 September 28, 2020 10:46AM

Just some reminders and why I like having a versatile team of detectors.

Monte 45 September 28, 2020 07:21AM

How about the Nokta FORS CoRe?

Kickindirt 47 September 28, 2020 07:04AM

How about the Nokta FORS CoRe?

Monte 49 September 28, 2020 07:48AM

Re: How about the Nokta FORS CoRe?

Kickindirt 38 September 28, 2020 09:15AM

"What means "IMB?----Or did I miss it?" ... My initial post: Intense Mineral Body N/T

D&P-OR 38 September 27, 2020 09:01PM

Re: "What means "IMB?----Or did I miss it?" ... My initial post: Intense Mineral Body

D&P-OR 40 September 27, 2020 10:39PM

Re: How about useable detectors for very high mineralization, pea gravel, rocks and IMB's?

RickUK 46 September 27, 2020 08:04AM

Re: How about useable detectors for very high mineralization, pea gravel, rocks and IMB's?

UtahRich 41 September 28, 2020 12:02AM

RickUK, nice to read your site history and search info.

Monte 40 September 27, 2020 09:14AM

Re: How about useable detectors for very high mineralization, pea gravel, rocks and IMB's?

Timbertodd 51 September 26, 2020 03:51PM

Comments about your MXT and Apex experiences.

Monte 59 September 27, 2020 01:05AM

Re: How about useable detectors for very high mineralization, pea gravel, rocks and IMB's?

D&P-OR 56 September 26, 2020 02:37PM

"Try the CTX out there also Monte---you'll love it!thumbs up" ... Nope.

Monte 61 September 26, 2020 07:50PM



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