G’day: Of course, aluminium is only pronounced AL-YOU-MIN-IUM
when it is properly spelt - in properly civilized countries, eh?
Anyway, I think that I was under the impression that aluminium
has a higher albedo than silver because I used it for front
surfaced mirrors in my post-war gadget-building for IR
spectroscopy, but it really was a hell of a while ago, and I’ll
concede to those who say silver is better. However, the tarnish
on silver (mirrors included) is due almost entirely to silver
sulphide, which is black. Silver oxide is a grey-white; silver
does not oxidise easily. All industrialised cities have a good
deal of sulphur in the atmosphere, which explains tarnishing
there. If you don’t want your silver to tarnish so quickly, come
and live in New Zealand! 
(-:
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/ / John Burgess,
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/ //\ johnb@ts.co.nz
/ / \ \
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