8 Reales 1825 Potosã­ Fake/Counterfeit

Not bad Moneditis - John Lorenzo for a second thought he was all alone in the world of XRF and SEM/EDS analysis with the Spanish-American Reales and the new Gurney/Nichols/Lorenzo (GNL) book being published NOW by the American Numismatic Society for early 2015 (probably) which goes into these analyses in GREAT DEPTH.
To your coin I am sure Bob would be interested in these round windows - we have discussed previously drooping windows and there tie-in to certain contemporaries.
This is my take on your analysis - The Si,Na,Cl,Al,S, Mg & Hg (in this case) all are termed organic outside SURFACE contaminants and are NOT part of the metal alloy. What is important is the Silver, copper, lead, arsenic and iron and the absence? of gold and platinum. Particularly gold as sometimes platinum detection is difficult on older or hand held cheaper instruments. This seems to be a later piece - however - its recommended to go back to the analyst and MAKE SURE gold analysis was part of the assay test. Normally when we see Ag < 90% its brings up the possibility of a debased silver alloy even a few percentage points - normally levels are ALWAYS > 90% even with all these surface contaminants ... this probably is a Class 2 contemporary counterfeit - but I will leave that judgment to Robert Gurney (swamperbob). The lead values look normal as well as the copper for a regal - but again where is the platinum and gold. Are all these organic suface contaminants forcing the Ag value just below 90%.
Your empirical testing list to determine regals of the period should be: Ag, Cu, Pb, Au, Pt, Fe, Ni & As. Hg is recommended as most counterfeiters sometimes used a Hg/Ag amalgamation and then pasted this mixture to a debased underlayer host coin. Not the case here since Hg here is normal in its trace background as being an ore refined/derived alloy contaminant value.
See my September 2013 Mexican Numismatic Association Paper on the War of Independence XRF Study on the Chihuahua Eight Reale cast silver pieces for a recommended assay list. You do need to be a MNA member of course to access the past journals in the Library link at the MNA site.
At this point I am thinking slightly debased Ag silver issue and Class 2 GNL type. But again - what is the Gold content? - if present ... expect it between 0.1-1.0% as with platinum (Pt). If gold is less than <0.01% then you are almost forcing this piece as a Modern Strike (i.e., 20thC).

John Lorenzo
United States

In my memory, I don't see any keyhole windows for Bolivian 8R in any concerned threads. Keyhole windows are always seen on Mexican 8R. According to swamperbob's theory, keyhole windows is one of the indications of Class 2 contemporary counterfeit.

If this coin is an original, it will be a challenge to swamperbob's theory. Do I interpret wrong? Henry

As we discussed and I am not ducking the punch wonghinghi but Material Analysis is strongly SUGGESTING 20thC modern since gold and platinum <0.01%. The gold and platinum coming strictly from silver refining. But as we discuss in the GNL book and as Bob has discussed in this forum this XRF testing is just one factor. He will chime in soon enough with this topic header. Personally, I would not touch this piece with a ten foot pole. To be clear the real desirable CC8R's are off-metals like copper and brass (Class 1's). The late 19thC debased silver Class 2 much less desirable in a collection of contemporary 8R's. Silver plated Sheffields of course VERY DESIRABLE and even more so if GIII countermarked with either a real or fake countermark. Even with silver plated Sheffields the gold and platinum MUST be there ... remember once the Ag drops in certain issues ... Au and Pt may be less than 0.01%. But with Ag~90% here the lack of gold SPELLS modern ...
Can't recall this type of window but unlike Bob who has been looking at these 40+ years ... me only 5 years he may have seen this ANIMAL before <BG>.

I don't see anything wrong with that punch. It's the same as the one found on the following example fo the rare "J" assayer of the same date:

http://www.coinfactswiki.com/wiki/I...38-0484g.jpg

Realeswatcher - this is a typical assay from a SEM/EDS device that reveals both ORGANIC & INORGANIC (METAL) constituents.

XRF just reveals INORGANIC (METAL) constiuents.

Realeswatcher - what component on coins makes them oxidize the most or in simpler terms - tone - CHLORINE (ORGANIC).

What is the second most common ingredient but PRIMARILY relevant to just on copper coins that make them rust or tone - SULFUR. Particularly heavy loads for example on British copper coins from the 18thC as in U.S. Colonial coins. Pary's Mine ... etc. <VVBG>.

Both are organics in this realm of Material Analysis. Oxygen? What gives the 8R its toning? Copper. As in copper oxides ... there are about six forms of copper oxide yielding various colors. Hence the term rainbow hue on U.S. Morgan dollars from the New Orleans Mint - only on one side are they normally toned ... top coin in the bank roll ... <VVBG>.

BTW - Realswatcher - holding a coin by the edge - STILL - introduces chlorine contamination to the obverse and reverse. Cotton Gloves. Just a FYI if you own any Proofs not in TPGs.

Just FYI.

John Lorenzo
United States

Hello moneditis, can you share the edge pictures of this coin? You can also examine your coin's edge and see whether there are two opposite overlaps, since this is one of an indications to say it is an original.

Don't rely too much on experimental (physical) parameters as there could be errors involved during measurements. Henry

Over time the organic layer builds up but we can not be sure of the higher value so normally you can not extrapolate up in a linear fashion to 95% but it does indicate its higher than 89%. It does suggest its high silver at the appropriate level but again it lacks the gold and platinum of the period. We also have the L. Beck silver surface enrichment factor. Indeed this is not an easy decision here - as Carlos has indicated it has a good punch - to be CLEAR - over 500 examples I have never come across a genuine example that did not have good Pt/Au for a regal 8R. It MUST have these two trace metals ... if die linked as regal I would re-run the tests in different spot areas for confirmation on the lack of Au & Pt.

John Lorenzo
United States