way is that we imply that there is something of great value on their property when this is most likely not the case at all. There is also the implication is that much excavation and mess will be required to find the "treasure." People will respond to a request for permission to detect by not allowing us on the property to find their "treasure" because they think we will profit by it, or that our search will take a long time and destroy their lawn and flower beds.

Often our "treasure" is a few old coins or relics often of small value - $20 or less, many times much less! How best to convey to others that our pleasure is mostly in the research, search and discovery more than the value of what we find? That the cost of our machines, gear, time and travel expense usually far exceed the cumulative value of our finds?

I suggest we adopt the term "detectorist" as Robert Sickler explains in his book, or even better, "metal detector hobbyist."  As a metal detector hobbyist, people get the idea that this is a hobby... something done for fun and pleasure, not for profit.

Just some food for thought - maybe this different label might help open some more doors and make the difference between permission to detect and hearing a "no."

helpers. From the leader to the helpers they are all volunteers.  They don't get paid for any of the tasks they perform for the club.  It is their personal time they are giving to you.  It is a gift. Don't look the gift horse in the mouth.

So, what kind of helpers are needed?  Someone to keep the website, write and mail a newsletter, a treasurer, someone to run the 50/50 and raffles, someone to get prizes for find of the month and the raffles.  If you have group hunts or planted hunts, people need to organize those as well. No one person can do it all.  So, if you just had the helpers I listed, you'd need seven people willing to volunteer to run parts of the club. Yes, volunteer.  That means they do this work for free, and no doubt it is work.

Where do you find dedicated people with enthusiasm or at least a sense of commitment to do all the thankless work?  Don't say it's not thankless... 90% of the time, it is.  There are always rabblerousers who pay their membership fee, offer no volunteering or help, and want the world on a platter.  This is not a retail store, one does not just "buy" a membership.  It's an organization of people with a common interest and beliefs.  Friendship and fraternity are key elements of a successful hobby club.  You have to put something in (more than a membership fee) to get something out. If you need or want something from your club, ask nicely and be willing to help.

I was musing just now what a full-service metal detecting club would cost to operate, a country club of detecting.  To pay for the wages for the things most club members do for free would probably be $50,000 to $100,000 a year.  Let's see, say 50 members, that's $1,000-2,000 per year for a full service metal detecting club.  That's a pretty exclusive detecting club!

I just thought of more people you'll need... a photographer (maybe someone to make short videos too) and someone to organize the yearly dinner.  That's 9 people now.  Where was I? Oh right, where do these people come from? The simple answer is I don't know.  Some have boundless energy, but only for a short time.  Others have family and job obligations that keep them from participating.

Another thing clubs and club members should be doing is lobbying government officials for metal detecting rights.  And don't even think about asking for privleges unless the club is also advocating responsible and honorable behavior and training members in proper recovery techniques.  Sadly, all it takes is one person to ruin a club's reputation or to close public sites to metal detecting.

So wow, this idea of a simple metal detecting club is getting really complicated, isn't it.  No wonder so many have fallen by the wayside.

So, you need a meeting place too if you're going to have meetings.  A place where everyone feels comfortable and interested members of the public can stop by.  Public places such as libraries, historical societies, and parks are all great free places to meet. These reputable and respected locations have the added bonus of lending a sense of acceptability and legitimacy to your club.  Not much fun if no one shows up to your meeting.  How do you get people to make the metal detecting club a priority and show up every time?  Is it the finds contest, the raffles, the prizes, a presentation or demonstration, a dinner or a group hunt?  Different things appeal to different people, and with a small group, it's hard to please everyone every time so keeping activities varied is a help.

A club should have a public service component.  The club can have a clean up day at the park, offer metal detecting services to local law enforcement, or any of 100 other ways of giving back.  Every member should do something either individually or as part of the group.  Why would you want this?  Because it's great publicity for one, and secondly it shows that you do truly care about your community - a group of takers and users are not going to get much sympathy from local officials or the public when their rights are at risk.

Clubs should also be members of the FMDAC,The Federation of Metal Detecting and Archaeological Clubs.  I have not been a great fan of the FMDAC and have found their responsiveness to members to be lacking.  However, they are an organized front that represents and fights for our hobby.  The more involved we are with FMDAC, the more they can do for us.

Now about the internet, which my aunt still considers a "fad," I promise it is not.  There are still quite a few detector users who are not computer users though.  Hard for many of us reading this online to believe, but it's true.  That said, I think all clubs should have a web presence.  Even if the club pays someone's teenage child a few dollars a month to keep a website going.  Without local detector dealers recommending your club, how will people find it?  A virtual club in addition to the physical club helps keep people connected, even when they may not be able to dedicate much time to their club or detecting.  It also serves as a valuable resource to publicize the club and get new members.

Speaking of new members, ongoing recruiting needs to be a goal of the club.  If you are not attracting new members, eventually there will be none.  People stop attending club meetings for many reasons, some of which can be when they get busy with other hobbies, lose interest, disagree with others, have family issues, or illness.  Clubs should have a goal of attracting new members and keeping them, maybe even offering some sort of bonus or award for existing members signing up new members.

Awards and prizes.  I don't know about you, but I no longer need a silver half dollar as a "prize" when I win find of the month.  I already have the find of the month, what greater reward do I need?  Recognition is great, but a simple certificate serves me just as well as a coin.  The thrill of competition is what keeps me going, rather than the promise of a reward.  In a club I was a member of we had categories for find of the month.  Best coin, oldest coin, relic, jewelry, button, etc. Back then I worked hard at getting something to enter in each category.  I remember a friend and I went out one day specifically looking for buttons to enter in the contest.  Now that kept things interesting and got us thinking outside the box about our usual detecting.

be sensitive to gold targets. That's why most gold detectors sold have a freq. starting at 15 Khz and higher. The detectors sold with general hunting in mind have operating freq. starting from between 5 to 10 Khz." 

Minelab’s E-Trac and Explorer use FBS which simultaneously transmits, receives and processes 28 frequencies from 1.5 kHz to 100 kHz.
White’s V3 uses three frequencies 2.5 kHz, 7.5 kHz & 22.5 kHz and operates in the frequency domain only.
White's MXT is 14 kHz
White's XLT is 6.5
White's DFX is dual frequency 3 kHz and 15 kHz
Tesoro models use various single frequencies:
10kHz, 12kHz, 14.3 kHz, and 17.5 kHz. 
Tejon ranges 17.2-17.6 kHz.
Garrett Ace 250 uses a 6.5 kHz operating frequency.
Fisher CZ3D and Fisher CZ20 are both dual frequency, 5 kHz and 15 kHz
Fisher F5 - 7.8 kHz.
Fisher Gold Bug - 71 kHz

So, if you're looking for gold only you want a machine that handles the higher frequencies.  Hence, the Fisher Gold Bug at 71 kHz, and PI (pulse induction) units, but let's not get into PI units as most of us do not want to do old coin hunting in trashy sites on land with a PI. 

The multiple and dual frequency machines should always be able to turn up more targets than a single frequency machine.  Theoretically, if you have "cleaned out" a site with your 6.5 kHz White's XLT, and then come along with a 17.5 kHz Tesoro Lobo, you will find targets you missed and that were undetectable with the 6.5 kHz White's machine.

The result of this is that a newer multiple frequency machine will be able to find more targets than the single frequency machines (not necessarily older coins).  So the newer multiple frequency machines, including the old Fisher CZ and Minelab FBS machines will do better than a single frequency unit. 

This is where I start thinking about accuracy of target ID - beeping over metal is not enough, I need to know if it's worth digging or not.  How does the number of frequencies affect the target ID?  Is a dual frequency (or more) machine going to ID targets more accurately than a single frequency unit?  It seems like this would be the case.  Certainly in my experience I have found that my Minelab FBS machines are the most accurate ID machines I have ever used, and they are accurate at good depth as well, though any machine will start to drop off on target ID at the edge of it's detection range.  I have seen some reports that users of the White's V3 are also reporting more accurate target ID.

Now about finding gold.  How does operating frequency affects the detectability of lower conductive metals?  Gold is always difficult as it is alloyed with different metals.  10k gold is about 40% gold, so the detectability of a 10k ring is somewhat dependent on what the other 60% of the ring is made of.  Due to this variability in alloys, shapes and sizes of gold rings and jewelry, I do not think we can even predict accurate results for one frequency or brand or model of detector being able to find more gold while land hunting homes, parks and schools.  Thin gold rings are smaller targets and will be picked up better by a higher frequency, so a higher frequency may have a slight advantage there.  For purposes of this discussion, I'm keeping this focused on coinshooting and detecting at parks, schools and homes.  Nugget hunting and beach hunting would be different styles of detecting.

I think it comes down to what we have all been told in the metal detecting press and on online forums ad nauseam.  The only way to find more gold jewelry targets on land is by digging more junk and trash targets that fall in the pulltab range on ID machines.  If you do not have target ID, you will dig more junk, hence the potential is there for more gold.  So, do users of non-ID machines find more gold?  Maybe.  But their trash-to-treasure ratio is much higher than someone using a target ID machine.

And just a brief not about coils here too, as I feel these play a role as well.  The two current most expensive popular machines are the White's V3 and the Minelab E-Trac.  Both use DD (double D) coils.  In my experience the DD coil covers ground better than a concentric.  The Minelab I have found separates signals well, even penny size targets at depth.  Better ground coverage with good separation means you will be able to recover more targets and there will be fewer missed targets due to not overlapping sweeps or target masking.

So, why a newer machine?
1. Multiple frequencies = more detected targets
2. More accurate target ID = more signals that say "dig me"
3. DD coils = better coverage and separation

I am curious as to why dug indian heads and early wheats come out of the ground with such nice green patina.  It's too much for me to believe this is just chance that coins after the mid-1920's do not exhibit this patination. Two cent pieces minted from 1864 to 1872 also have these same characteristics.
 
I believe the answer lies in the "5% tin and zinc" content of bronze cents.  I cannot find a reference to the specific percentages of zinc and tin used.  Sometime in the early 1920s, the percentage of zinc must have been increased and tin decreased.  I can find no reference to this change, but I would be very interested in finding one.

Tin is a key element in bronze.  The properties of tin state that it is not easily oxidized, prevents corrosion, resists corrosion from water, but can be attacked by acids, alkalis and acid salts.  These are exactly the properties that would make the early cents better preserved than the later ones.

Anyone who has dug an eaten up modern penny knows how zinc weathers in the ground.  So, this also indicates that an increase in zinc would make the surfaces more easily corroded.

Follow up #1
The composition is the "same" only to the extent that it is "5% tin and zinc" this is a vague reference.  I can find no references that specify the specific percentages of tin and zinc.

My theory is the older "green" cents are maybe 3% tin and 2% zinc and the non-green are maybe 1% tin and 4% zinc.

It has little to do with the time in the ground, as these earlier cents even read differently on the meter of many metal detectors, which says to me that it is clear there is some difference in metallic content.  The conductive value of older cents on the Minelab E-Trac is 33-36, the conductive value of later cents is 42-43.  And this can be shown in the ground and in air tests with dug and non-dug coins, so the time in the ground is not significant.

Follow up #2
Well, the minerals or ground effect only prevent the green patination from forming or eat it away.  If the soil is "acid, alkali or contains acid salts" then the tin will be attacked and the coin will have a rough corroded surface.  

Where the soil is fairly neutral, the tin provides some protection against corrosion.  There is some oxidation/corrosion occurring in the ground as that is what makes the cent turn green.  

My hypothesis is a greater amount of tin in the mix helps keep the surfaces smooth and even, preventing (in more neutral soils) the rough or heavy corrosion as seen in many copper coins recovered from fertilized farm fields.

I find that in my soil, which is fairly stable and neutral that older small cents tend to have this smooth patination.  Coins that have been fertilized or are in clay type soil do not.  Even modern coins in clay type soil are heavy corroded.

Overall I guess my question is not, "Why do they turn green?" but rather, why are the early cents so much better preserved than later cents when supposedly the metals are the same.  I am saying is the metals must not really be the same, and the ratios of tin to zinc within that 5% have been altered.

Another random thought is wondering if the addition of tin to the copper coating on modern zinc pennies would improve their corrosion resistance. Hmm...

Follow up #3
Wikipedia shed some light on some things:

Brass is any alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. In comparison, bronze is principally an alloy of copper and tin.

Aluminium makes brass stronger and more corrosion resistant. Aluminium also causes a highly beneficial hard layer of aluminium oxide (Al2O3) to be formed on the surface that is thin, transparent and self healing. Tin has a similar effect and finds its use especially in sea water applications (naval brasses). Combinations of iron, aluminium, silicon and manganese make brass wear and tear resistant. A well known alloy used in the automotive industry is 'LDM C673', where the combination of manganese and silicon leads to a strong and resistant brass.

Selective leaching, also called dealloying, demetalification, parting and selective corrosion, is a corrosion type in some solid solution alloys, when in suitable conditions a component of the alloys is preferentially leached from the material. The less noble metal is removed from the alloy by microscopic-scale galvanic corrosion mechanism. The most susceptible alloys are the ones containing metals with high distance between each other in the galvanic series, eg. copper and zinc in brass.

Follow up #4
I discovered this text from Jevon's 1875 book, Money and the Mechanism of Exchange:"

Bronze Coin.
XI.11  It was known, even in prehistoric times, that a small quantity of tin communicated hardness to copper, and the ancient nations were familiar with the use of bronze thus manufactured. The French Revolutionary Government melted up the bells of the churches seized by them, and the sous de cloche,as they were called, made from the bell metal, were superior to coins of pure copper. Yet curiously enough no modern government thought of employing a well-chosen bronze for small money, until the government of the late Emperor of the French undertook the recoinage of the old sous in 1852. This recoinage was carried out with great success.

XI.12  Between the years 1853 and 1867 coins to the nominal value of about two millions sterling, consisting of 800 millions of pieces, and weighing eleven millions of kilograms (10,826 tons) were struck, in addition to a subsequent issue of about 200 millions of pieces. The experiment was in almost every way successful. The ten and five-centime pieces now circulating in France are models of good minting, with a low but sharp and clear impression. They were readily accepted by the people, although only weighing as much as the sous rejected in the time of the Revolution, namely, one gram per centime, and they are wearing well.

XI.13  The bronze used consists of 95 parts of copper, four of tin, and one of zinc. It is much harder than copper, yet so tough and impressible that it takes a fine impression from the dies, and retains it for a long time. It cannot be struck except by a press of some power, and thus counterfeiting is rendered almost impossible. It can hardly be said to corrode by exposure to air or damp, and merely acquires a natural patina, or thin dark film of copper oxide, which throws the worn parts of the design into relief, and increases the beauty of the coin.

XI.14  Bronze has since been coined by the governments of England, the United States, Italy, and Sweden, and it seems probable that it will entirely take the place of copper. The German government is now using bronze for the one-pfennig pieces."

My conclusions drawn from this: Bronze for coins was a new idea in 1852.  The specific formula is listed as containing 4% tin and 1% zinc.  This is most likely the formula used in the first Indian head cents in 1864, as this new bronze alloy would have proven itself with use in Europe.  This supports my contention that the earlier cents have a higher (4%) tin content, and that is why they corrode less and maintain smooth green surfaces.  We know that the tin was removed from cents completely in 1962, but I contend the amount of tin was reduced before 1962.

Domestic and foreign coins manufactured by mints of the United States (1965) states: "Alloy of 95% copper and 5% zinc coined 1944-46 by order of Secretary of the Treasury of Dec. 16, 1943, pursuant to act of Dec. 18, 1942."

According to the same document above, the US mint was producing bronze coins for other countries. In 1917-1919 the US mint produced coins for containing 95% copper, 3% tin and 2% zinc for Peru. In the early twenties, coins were minted containing 95% copper, 1% tin and 4% zinc as early as 1921 (Indo-China) and 1922 (Costa Rica).  In 1942, coins made for Surinam were 95% copper, 1% tin and 4% zinc.   It would seem odd that they would create a unique alloy for these small runs of foreign coins rather than use the "stock" US bronze alloy.

This points to the late teens as a target timeframe that tin was first reduced from the bronze cent, giving a speculative timetable that looks like this:
1864-1916   95% copper, 4% tin, 1% zinc
1917-1920   95% copper, 3% tin, 2% zinc
1921-1942   95% copper, 1% tin, 4% zinc*
1944-1946   95% copper, 5% zinc
1947-1962   95% copper, 1% tin, 4% zinc
1963-1982   95% copper, 5% zinc

*In testing wheat cents with a metal detector, the majority of coins having a arbitrary numerical CO value of 36-41 or were minted before 1942.  Almost all coins minted 1944 and after had CO values of 42-44.  From this interpretation the early 1920s coins may have been somewhat experimental or perhaps normal variations in batch consistency, and the reduction to 1% tin did not occur until 1947.

Follow up #5 (October 1, 2013)

I discovered a reference to the composition of the two cent pieces which exhibit similar characteristics to the early small cents. 'In a Dec. 8, 1863 letter from Mint Director James Pollock to Secretary of the Treasury Salmon P. Chase, the Mint director recommended a 2-cent coin be
introduced in what was called “French bronze.”'

According to wikipedia, French bronze is a form of bronze typically consisting of 91% copper, 2% tin, 6% zinc, and 1% lead.

First portion of The Coinage Act of April 22, 1864