Pinpoint Probes

Garrett Pro-Pointer

An extremely useful metal detecting accessory is an electronic pinpoint probe; a hand-held miniature metal detector, identifying all metal by audio and vibrating. This gadget helps identify the exact position of the find in and out of the ground so you can not only avoid damaging your find but speed up find extraction considerably. Probes have other uses too. You can check the surface for shallow finds before you dig, which is especially useful when searching sensitive areas like lawns or when searching for a recent loss – you usually only need to check the shallow signals. Probes with a limited range, perhaps no more than an inch on a coin-sized object, have been around for a long time but a few years back Garrett brought out the Pro-Pointer which has a greater range and a larger price tag but is so much better at pinpointing than the old style probes. I bought a Garrett Pro-pointer when they were first available in the UK and have had 10 years of reliable service out of it but recently it started sounding-off (falsing) for no apparent reason, even with a new battery, which made me think it had come to the end of its working life.  I had a look around to see what was available and it seems almost every metal detector manufacturer now makes these probes in many colors. But the cost of some of them is bordering on the ridiculous – you could easily buy a good, brand new, entry level metal detector for the price! There are quite a few tests on YouTube and one thing that struck me was that the Chinese had got in on the act and they have a probe available at less than twenty pounds or twenty-five dollars, which includes holster, lanyard and shipping! The model in question is called a GP-Pointer and it tested quite well on YouTube so I thought I would give it a try. It is almost identical to the Garrett in appearance. Switching on takes about 3 seconds; whereas Garrett is instant. The GP is not quite as sensitive, nor as loud, nor vibrates so strongly as the Garrett. I didn’t find any of this to be a problem even when wearing headphones but I do have good hearing and did not need to wear thick gloves at the time. It may be difficult to use in a noisy environment and by anyone with poor hearing but for its price, I found it a great tool for the money.

GP-Pointer

As a footnote, I did a Google search for ‘repair Garrett Pro-pointer’ and found some YouTube videos which show you how to fix the fairly common falsing problem. I have taken the advice and had a go at repairing mine. So far so good, it still works but I have yet to field test it.

Diamond Orbs

In TheSuccessful Treasure Hunter’s Secret Manual, I looked at thermal and electrical conductivity as a possible explanation as to why some metals produce stronger auras than others. What I discovered through experimentation is that different metals produce different auras and fortunately precious metals produce the strongest auras. In other words a smaller amount of gold or silver will produce an aura than is the case with base metals. This stuff is so cutting edge that I’m afraid I don’t know all the answers. I do recall that when I was doing a lot of beach treasure hunting in the summer evenings, when the crowds had left, that coins coming out of the sand were always quite hot to the touch. The mechanism is presumably emission of infrared radiation selectively absorbed by metals from the sun although it could just as likely be metallic interference with the earth’s magnetic field. It doesn’t matter too much, as it is results in finds that we’re after, not a degree in physics. A useful way of comparing metals seems to be thermal and electrical conductivity, I must stress these may not be the only factors or even the correct factors that determine aura strength but they do tie in quite nicely with my observations.

Silver has a thermal conductivity of 420 Watts per metre-Kelvin and an electrical conductivity of 62,000,000 Siemens per metre. Pure copper has a thermal conductivity of 370 W/mk and an electrical conductivity of 59,500,000 S/m. Gold has a thermal conductivity of 315 W/mk and an electrical conductivity of 45,000,000 S/m. Pure copper has conductivities in between gold and silver, however copper is normally found alloyed with zinc or tin forming brass or bronze respectively, which have much lower conductivities, typically a thermal conductivity of 125 W/mk and an electrical conductivity of 15,000,000 S/m. Soil, sand and water have thermal and electrical conductivities around 1 W/mk / S/m or less. Diamond, interestingly has the highest thermal conductivity of any known substance at 1000 W/mk but such an extremely low electrical conductivity it can be considered to be an insulator. Unfortunately I couldn’t afford a large heap of diamonds to test whether they produced auras but I said it might be something worth looking out for. I was sent the photo from a reliable source who claims it is a diamond aura. I must say it is a very unusual aura photo and I haven’t seen anything quite like it before. I would like to see a photo of the diamonds though, which might be available in due course.

Round Pounds

The new 12-sided £1 coin became legal tender on 28 March 2017. The round £1 coin lost its legal tender status at midnight on 15 October 2017. There are still 169 million out there, which have not been returned to the mint. I am sure we will be finding them with our metal detectors for many years to come, but from what I have heard and read a lot of detectorists think they are now worthless. NOT TRUE!

Until further notice most UK High Street Banks will exchange round pounds for account holders at full face value. Some will exchange them over the counter; others will want them deposited into accounts. The Post Office has arrangements with most UK High Street Banks, as well as its own bank, and will also accept round pounds for deposit into a bank account.

There are currency exchange companies who will exchange withdrawn coins. One is currently paying 85% face for round pound coins and 75% face for withdrawn British decimal and pre-decimal coins. Bear in mind that pre-decimal copper (bronze) and brass coins are worth more than their face value in scrap. One old penny, weighing 9.45 grams, is now worth about 3p. In contrast the nickel-brass round pound weighs 8.75 gram and would be worth slightly less than 3p as scrap. Nevertheless that is an option if the coin is mutilated and not acceptable elsewhere.

Further details of profitably disposing of withdrawn and foreign coin finds will be found in Treasure Hunting for Profit.