Author Topic: Sudan: Copper Nickel / Aluminium Bronze  (Read 1850 times)

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Offline squarecoinman

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Sudan: Copper Nickel / Aluminium Bronze
« on: August 30, 2012, 03:09:30 PM »
I need some help with a small problem .

According to the central bank of Sudan the 25 Ghirsh 1987 is

25 Piasters 1987 Cooper - Nickel , weight 4,7 gram

According to the rest of the world it is a 25 Ghirsh 1987  Aluminium Bronze  10 gram

I know the weight is 10 gram , I know the diameter , what i do not know is what material it is made of , how can i find out if it is Aluminium Bronze or if it is Copper nickel

I would love to have some help on this , what i do not need is a reference to a catalogue ( like Krause ) I know they write aluminium bronze , I also know that the Central bank writes that all the other coins from that period are Aluminium bronze

is there a way to test this ( a simple test ? )

scm
World square coin book 1900-2000

Offline FosseWay

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Re: Sudan: Copper Nickel / Aluminium Bronze
« Reply #1 on: August 30, 2012, 04:03:43 PM »
I'd have thought just looking at it should be sufficient. Cu-Ni is 'silver' coloured, while aluminium bronze is 'gold' coloured. Also Al-bronze is lighter, so the coins have a feel that is closer to aluminium than to Cu-Ni. Compare the pre-WW2 French francs (the ones with the same types as those issued in aluminium in the late 40s and 50s).

Offline africancoins

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Re: Sudan: Copper Nickel / Aluminium Bronze
« Reply #2 on: August 30, 2012, 07:32:55 PM »
The Schon catalogue of world coins sometimes has a different opinion than the U.S. "Standard Catalog of World Coins" on the subject of composition. When the books have those differing opinions it is usually Schon who is correct.

This is such case.... the Schon catalogue says "N-Me" (Nickel-Brass) for this type. Such an alloy is generaly Copper, Nickel and Zinc and "yellow coloured".

Copper-Nickel - is not always a silvery colour...  The British 20 Pence coins are a sort of light brown generally due to the high Copper content.

Thanks Mr Paul Baker

Offline FosseWay

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Re: Sudan: Copper Nickel / Aluminium Bronze
« Reply #3 on: August 30, 2012, 07:52:15 PM »
Are UK 20ps anything other than 75% Cu 25% Ni? I can't say I've particularly noticed them being brownish or otherwise different from (pre-2011) 5p or 10p coins or 50ps. The Royal Mint went through a long phase (which lasted from the introduction of Cu-Ni coinage in 1947 to shortly after decimalisation in the early 70s) when its Cu-Ni coins were often streaky, but whatever caused this was ironed out well before the 20p was introduced in 1982.

A good example of what a Cu-Ni coin looks like when it has a higher than normal Cu content is the 1969 5 Mark coin issued to commemorate the 20th anniversary of the German Democratic Republic. One of the variants of this is in 90% Cu 10% Ni and it looks definitely reddish.

That said, I can understand confusion between nickel-brass and aluminium-bronze is much more likely. Personally I don't generally differentiate between the two in my records, because IME there aren't any types that are distinguished solely on the basis of a change from one of those two metals to the other. If the two don't 'meet' numismatically in a given country's output, then there's limited point in making the distinction - at least that's my logic!  :)

Offline Afrasi

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Re: Sudan: Copper Nickel / Aluminium Bronze
« Reply #4 on: August 30, 2012, 11:33:57 PM »
The Schon catalogue of world coins sometimes has a different opinion than the U.S. "Standard Catalog of World Coins" on the subject of composition. When the books have those differing opinions it is usually Schon who is correct.

I totally agree with this.

But looking at my two pieces of the mentioned coin I am not sure about the composition. An absolut uncirculated shiny piece looks like nickel-brass, a heavyly worn piece in about fine condition looks like aluminium-bronze.
In the last days I scanned some of my newer Sudanese coins to show the main variants. (I will show them here soon.) So I had a closer look again at these coins and - just to say it carefully: I got the impression the used material is often not homogenous. Perhaps it is even impossible to describe the metallic composition in a logical manner ...
But I never saw your mentioned coin in copper-nickel! ;-)

Offline squarecoinman

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Re: Sudan: Copper Nickel / Aluminium Bronze
« Reply #5 on: August 30, 2012, 11:37:55 PM »
I totally agree with this.

But looking at my two pieces of the mentioned coin I am not sure about the composition. An absolut uncirculated shiny piece looks like nickel-brass, a heavyly worn piece in about fine condition looks like aluminium-bronze.
In the last days I scanned some of my newer Sudanese coins to show the main variants. (I will show them here soon.) So I had a closer look again at these coins and - just to say it carefully: I got the impression the used material is often not homogenous. Perhaps it is even impossible to describe the metallic composition in a logical manner ...
But I never saw your mentioned coin in copper-nickel! ;-)

Afrasi I also do not think it is copper nickel , but it is from the central bank from sudan so i felt i had to check it , but like i wrote before the weight was also wrong , and they call it a 25 piaster , and the size was also wrong ( just a little )

my feeling is nickel brass , the planchets where provided by the RBM in the Uk , so maybe they can help

thanks scm
World square coin book 1900-2000