Amazingly enough, copper is not simply copper. The copper that we see in our dogs is really a form of the agouti locus, and is named A.

Here is a chart describing the different effects concerning each sub-allele, listed in descending order of dominance. This is based on mouse genes, not dog genes.

Allele	Phenotype	Occurs in Aussies	Color Explanation in dogs
Ay	yellow	X	sable
Avy	viable yellow		yellow
Aiy	intermediate yellow
Aw	light-bellied agouti		agouti with a light stomach (in rats, Berkshire)
Ai	intermediate agouti
A (+)	grey-bellied agouti (wild type)		wolf coloration
As	agouti-suppressor	X	Saddleback pattern (German Shepherds, for instance)
atd	tanoid
at	black and tan	X	like a black bi
ax	lethal non-agouti
am	mottled agouti
a	non-agouti		black
ae	extreme non-agouti		black

So what on Earth was going on there? Well, as much as I would love to explain all the different color variations (most are easily shown on mice, wish I had my old job back, breeding mice,  could have some nice pictures), I'm going to focus on the Aussie variations. These are:

Allele	Phenotype	Explanation	Genotype
As	full pigmentation	base with no tan points	AsAs - totally black Asay - running gold Asat - copper points mixed with black
ay	sable	sable	ayay - pure sable (no black) ayat - sable with black tipping
at	tan points	base color with tan points	atat - base color with tan points

So, using your Mendel squares, now you know how to breed for copper and breed OUT running gold!

Note: A is for agouti

At right is an image of an a^ya^y dog.