For interest of readers. Some 3-4 years ago or so I bought this coin at an UK auction, and did not record the provenance and did not record the weight. I subsequently had it graded by NGC. This coin to my knowledge is not recorded and searches for it are in vain. It is quite attractive and is NOT an OMS proof but rather either currency or specimen status. NGC calls it iron (note that apparent hairlines are in the perspex plastic:
Coin looks copper nickel, I did not weigh it, but it is magnetic. I am not that familiar with iron or steel coins but I still question it. It is the ONLY 1970 GB coin graded uncirculated, so that is interesting.
As per the conversation I had with Graham Dyer a few year ago and posted on the Predecimal forum, he said forget the denomination. These strikes were all about testing a metal mix and not necessarily struck in the year indicated - just like my sample half-crown in steel which he said was made in the early 1980s, long after the halfcrown ceased to be relevant. You really need it out of the slab and do a proper test to determine the metal content. The XRF below wasn't run against a standard, but will be approx. correct for alloy content. RONTEC EDWIN WinTools HALFCR 02.09.2009 (13:07) NT vers: 3.2 eng Eo:25.0 keV (TO:35.0 TI: 0.0) *** PUzaf results *** elem/line____P/B______B_______F________c______c(100%)__%error__h_ Cr K-alpha 116.4 1.03867 1.38738 10.74 12.31 17.4 * Mn K-alpha 5.7 1.04072 1.09146 0.68 0.78 64.7 Fe K-alpha 597.5 1.04269 1.02462 75.79 86.91 14.7 Can't get the numbers to line up, but the important figures are 12.31% Cr, 0.78% Mn and 86.91% Fe.
Wow, that looks to be mainly iron as well and would imagine with marked magnetic attraction. I wonder if it is the same alloy? I really thought iron would look different but especially on the OP halfpenny as it is quite brilliant and well struck excepting the center of the Golden Hind ship which also appears softly struck on your coin Rob.
The 12% chrome composition is stainless steel (400 series??). I think this alloy is magnetic but don't quote me.
Correct on both fronts. And a picture of science in action. And for comparison, a picture of this coin alongside a Huth pattern double florin in iron, but I haven't done a metal analysis of the latter. The iron is slightly duller in hand, but also 70 years older. I wouldn't lose any sleep over the quality of the strike, as if they are testing a new mix, they are bound to try a range of conditions to see what works best.
Mine graded MS67 at NGC, and frankly a fair grade - if that matters. I really wish I had gotten the dated 1952 half crown penny with design as Rob's!
I'd want them all as they would all have equal relevance within the collection. Grade is irrelevant as each is a one off and therefore rises above a 'mine's better than yours' discussion. Thinking aloud, metal mix tests might also explain the large number of late 60s off metal strikes. Most seem to be pennies or halfpennies which would provide a standardised relief for the experiment. The mint was striking for a large number of former colonies, including non-British. e.g. I have a 1967 florin struck on a Burundi 10Fr flan.
Yes indeed. I have one each of the 1964 through 1967 pennies in copper nickel and a florin struck on I think on a Hong Kong minor.
There are a few 1950s British West African coins struck in steel or other alloys, but just tests and not for British West Africa at all. I remember reading about them somewhere too but can't remember where.
Hmmm, I think I remember Nigeria or West Africa as you say perhaps shilling with "TRIAL" on the coins as well...
Yes, they did say TRIAL - Vice's book on British West African coins says they were struck in the late 1960s in an attempt to find a cheaper alloy to make coins from - that must have been where I read it.
I think what is important is the element chromium. This is a sign of stainless steel alloy which is interesting. I don't know if striking coins in steel are meant to be for cost saving but the times do align as copper prices shot up in early 1960s.
