5/3/18 Report - Found Cobs for Identification. Digging Into Your Ancestry. Finding 1622 Shipwreck Consellacion.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Some of My Ancestry.

Research can be very helpful and some of the most gratifying and helpful research can be into your own roots.  Above are some of my ancestors.  The first husband of the lady in the middle was Henry Dixon, who served in the Civil War.  She was born in 1845.

Back a few decades ago, my maternal grandmother was the only one in my family who seemed to know much about our roots, and she learned with some help that she had an ancestor who served in the Revolutionary War.  For us, that bit of genealogical research seemed quite an accomplishment, but the internet has made genealogical research, along with many other types of research, much easier and more productive.  In recent years I've discovered several veterans of both the Civil War and Revolutionary War in my ancestral line.  

I'd encourage anyone interested in history, and I know most of you are, to really investigate your family history, and if possible, go back and metal detect some of the ancestral home sites.  I was lucky enough to be able to do that a few times in the past, and finds included some of my old toys that were buried where I played with them.  Like I said before, no one knows a neighborhood like the the people that were raised there.

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I received these photos from Chris N. who says his friend found these in North Florida.  He wanted to know if anyone could help identify them.  I told him what I could make out.  The most obvious thing is that the small one is a Mexican cob, and probably a half reale. 

Feel free to send me your thoughts whether they agree of disagree with mine.

It can be difficult to identify cobs from photos alone.  You see a flat image, and generally can't see the edges  Photos often distort things.  

If you want people to be able to identify cobs or any kind of item, you can help them help you by providing as much information as you can.  Size, weight, and other information, such as where the item was found, can be a big help.  

Here is another.  Again, let me know what you think.

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... The Spanish merchant ship carrying the treasure, called "Consellacion," was traveling through Florida waters in 1622 when it went down during a hurricane.

In an undisclosed location off the coast of Key West, treasure hunters may be on the verge of finding the loot, filled with gold, silver, and emeralds...

Here is the link for more about that.

http://www.nbc-2.com/story/37463361/hunters-close-to-finding-395-year-old-sunken-treasure-off-florida-coast

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I'm thinking of having some coins graded by one of the grading companies and would like to hear from anyone that has done that.  How did it go?  What would be your recommendations?  PCGS, NGC or ANACS?

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The increase in surf that was predicted for Saturday has disappeared from the predictions.  It now looks like we'll have about three days of three to five foot surf with nothing higher.

Happy hunting,
TreasureGuide@comcast.net

2/11/16 Report - Surface Analysis Of Corroded Reales: Part II.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com

Yesterday I left off discussing the following excerpt from a study of seven 8-reales from the wrecksite of the San Pedro.  I'll discuss a little more of that study today.

Here is that excerpt (no. 3) again.

The large amounts of iron found in the concretions and as distinct films on the coins recovered from a buried microenvironment is consistent with the history of the site. The majority of the surfaces of coins 4325, 4327, and 4331 were covered with a layer of pure hydrated iron oxides, such as FeOOH.xH2O. The films are compact and of relatively uniform thickness. The deposition of this material is likely to have occurred during the salvaging of the João Diogo as a continuous film that was subsequently eroded/corroded away in areas to reveal underlying layers of silver halides. The absence of iron on coins 4315, 4030 and 4342 is a reflection that these coins are highly eroded and corroded and have very little concretion.

The authors of the study believed that iron oxide accumulated on the coins came from the Joao Diogo wreck, a later wreck that scattered over the San Pedro wrecksite.  I feel certain that if they later wreck was not in the area, there would still be some coins showing some iron oxide.  Cobs from 1715 Fleet beaches sometimes show the iron rust appearance.  All it takes is for a silver coin to rest on or near iron objects such as cannons or spikes.  I've commented on the rust-like residue seen on some reales found on Treasure Coast beaches.

As the last sentence in the excerpt suggests, layers of corrosion can also be eroded off of coins, especially when they are end up getting tossed about in the surf and sand.

In the same way that iron products get transferred to coins at times, a similar thing can happen with other metals.

In nautical archaeology galvanic corrosion is an important topic.  It was observed that copper sheathing would cause iron spikes to rapidly corrode, for example.  Also, cleaning by electrolysis makes use of a similar process.

Here is link to a web site about galvanic corrosion.

https://en.wikipedia.org/wiki/Galvanic_corrosion#Anodic_index

And here is a table showing how susceptible different metals are to galvanic corrosion.  The table shows copper as being more cathodic than iron, which means iron will be drawn to copper, as in the example I mentioned concerning copper sheathing and iron spikes.  Forgive my simple explanation. Chemistry was one of my least favorite subjects, and really don't know much about it.

Most Cathodic
Gold, solid and plated, Gold-platinum alloy	−0.00
Rhodium plated on silver-plated copper	−0.05
Silver, solid or plated; monel metal. High nickel-copper alloys	−0.15
Nickel, solid or plated, titanium an s alloys, Monel	−0.30
Copper, solid or plated; low brasses or bronzes; silver solder; German silvery high copper-nickel alloys; nickel-chromium alloys	−0.35
Brass and bronzes	−0.40
High brasses and bronzes	−0.45
18% chromium type corrosion-resistant steels	−0.50
Chromium plated; tin plated; 12% chromium type corrosion-resistant steels	−0.60
Tin-plate; tin-lead solder	−0.65
Lead, solid or plated; high lead alloys	−0.70
2000 series wrought aluminum	−0.75
Iron, wrought, gray or malleable, plain carbon and low alloy steels	−0.85
Aluminum, wrought alloys other than 2000 series aluminum, cast alloys of the silicon type	−0.90
Aluminum, cast alloys other than silicon type, cadmium, plated and chromate	−0.95
Hot-dip-zinc plate; galvanized steel	−1.20
Zinc, wrought; zinc-base die-casting alloys; zinc plated	−1.25
Magnesium & magnesium-base alloys, cast or wrought	−1.75
Beryllium	−1.85
Most Anodic

Note that zinc is near the bottom of the list.  It is very anodic.  That probably explains at least partly why zinc pennies hold up so poorly in salt water.  On the other hand, gold is at the top of the list and normally shows no effect of being in the water for centuries.

Excerpt 4.

Since the San Pedro de Alcantara site is an area of constant and aggressive surge action, erosion corrosion plays a major role in the deterioration of metals on this site. The coins 4342, 4030 and 4315 were found lying on top of the sediment and their much higher mass loss is a measure of the erosion effect. Prior to recovery, coin 4315 was lying flat on top of a thin layer of sediment in a shallow bedrock hole, which meant it was fully exposed to water and sediment movement, and this resulted in more than a 60% mass loss. 

I've commented about the loss of mass seen on many Treasure Coast beach-found cobs in previous posts.  Some are less than half of their minted weight.  Such coins likely come from exposed areas with rough surf like those mentioned in this excerpt.  Tumbling in the surf zone is surely a factor.

Excerpt 5.

Calcareous concretions, especially those that grow in tropical waters tend to be somewhat porous and good conductors for the corroding metal they cover (MacLeod, 1982). In contrast, iron oxide films tend to be poor ionic and electrical conductors and can passivate the underlying corroding metal. There is a clear discrepancy between the preservation of those coin surfaces that are covered by iron oxide films and those that are not. Where the surface of coins 4325 is covered by an iron oxide film the raised design is well preserved, while the surfaces without the protective iron have the design obliterated. Clearly the iron oxide films are providing erosion and corrosion resistance to the coin surfaces they cover. 

That does not require additional comment.

I've probably carried on with this too long, but many of my casual observations and conclusions were verified and elaborated by this study.  To me it was validation.  It added to my understanding of the processes involved.  I hope you found it as interesting as I did.

Whether you understand all of it or not (I don't) you might benefit from wading through it to take what you can from it.

I didn't comment on the parts the explain the corrosion processes, such as how silver coins develop different layers, even though that information also expanded upon some of my personal observations.

The main point in looking at this study is to reinforce the idea that if you study your finds and understand how they got to look like they do, you'll then be able to draw conclusions about where they have been and where they are coming from.  When you know something about the source of those coins, you'll have some good information about where to look for more of them.

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I received some good information relative to the proposed citizen archaeology permit.  I need to discuss that some day.

I also have some other good things too discuss in the future.

On the Treasure Coast beaches we've been having a small surf and will for a couple more days.

I have to go.

Happy hunting,
TreasureGuide@comcast.net

7/29/14 Report - How Small Silver 1715 Fleet Cobs Identified by Metal Detector Target ID. Cape Verde Storm Season Begins.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.BlogSpot.com.

Snall Mexican Cob Remnant Used In Test

Before I begin today, I need to make something clear.  The tests that I have been doing are not just about a single detector.  These tests, although they use a particular detector, illustrate many of the points that I've made many times in the past, such as the dangers and imperfections of target ID and discrimination.  They are real, and they can be very important.

Another point that I am making with these tests is that you have to know your detector to get the most out of it.  If you don't you could be missing a lot of good targets - perhaps the best targets.

One day, using five different sample gold jewelry items of different sizes, I showed that if you did not dig items identified as  pull tabs, you could be missing something like 40% of the gold items that you put your coil over.

Another Small Half Reale Used In The Test

One more important thing I am illustrating through these tests is a systematic method anyone can use to learn how their detector responds and what it is telling you.  That is perhaps the most important thing to learn from these tests.  These types of tests can be used with any detector and any type of target.

I looked at how gold was identified by one detector a couple of days ago, and a few pieces of silver yesterday.  Overall, I've found coin ID on the Ace 250 to be generally excellent, but gold not as good.  That is to be expected.  Gold items are unique in size and shape and even composition.  Gold items vary in purity and the alloys used.

Today I'm going to look at how the same detector identified three small beach-found silver cobs.  Two of the test cobs for today's test are shown above.

As with the other tests, I tested using four of the detector's modes: All metals, Coin, Jewelry and Relic modes.

For the small cobs I used a badly worn half reales, which, as is true of most cobs found on the beach, were significantly underweight. 

The first weighed 0.015 troy oz,, the next, .07 troy oz., and the third, 0.2 troy oz.

The top picture above shows a small cob remnant, which is so small and worn that it would be underweight for even a quarter-reale, even though it is a half reale.

It measures about 5/8 inch across at its widest and barely over one half inch long.

These test results are easy to summarize.  The ID in all four modes was the same for all three cobs.  In all four modes all three cobs were identified  as a nickel.

That isn't bad.  Yes, you can't tell the difference between a cob and a nickel with the target ID, but at least the cobs didn't ID as a pull tab or something else that you most likely would not dig.

I was surprised that the detector identified the very small reale (0.015 t. oz.) as a nickel.   This inexpensive detector very clearly detected a very small piece of silver.  Not bad!  And it did not ID it as junk.

That is good news if you want to use a detector like this for finding cobs.  I haven't used this detector in the field for that purpose yet, and the one serious deficiency of this test is that it was conducted on dry sand, not mineralized or wet sand.  That will be a test for another day, although I most likely would stick with my much more costly detectors if I were really hunting reales on a beach.  Another test for another day would be to see how much depth effects the results.  These tests were done on surface items.

As it is, I am pleased with the effectiveness of this detector.   My first field tests in an old yard and woods, went well, as did the tests that I conducted since then.

Questions remain to be investigated, but I am getting to know this detector and its strengths and shortcomings.  I learned that if I'm searching for gold, I need to dig items identified as nickels or pull tabs.  If I want to detect small cobs, I need to dig items identified as nickels. 

I haven't test larger reales yet.   The smalls identified as nickels, while the large (0.6 t. oz.) silver bullion coin that I tested yesterday, was identified as a half dollar.  This test did not test reales in between 0.2 t. oz. and 0.6 t. oz.   I'll have to do that some time.  I wouldn't be surprised if there are some in that range that will ID as a pull-tab.  We'll see.  For now, I know that the target ID would not cause me to miss small reales if I dig targets identified as nickels, or larger silver coins.


It is the time of year when the Cape Verde storms start coming across the Atlantic with greater frequency.  August through October are the peak months to watch for those storms.

Here is a link to a good article about the Cape Verde hurricanes

http://blog.chron.com/weather/2014/07/heres-why-the-atlantic-tropics-are-likely-awakening/


Right now there is a tropical disturbance about a 1000 miles southwest of the Cape Verde Islands that has a 70% chance of becoming a cyclone in the next 48 hours.

According to the predictions, the Treasure Coast will be stuck with a one-foot surf through next Monday.

Happy hunting,
TreasureGuide@Comcast.net