mordant question

Hi folks,
I was trying to make a copper mordant. I soaked a handful of scrap copper in vinegar water. At least, I thought it was scrap copper. Maybe one of the pennies was newer than I thought and so I got some zinc? I sure don't think there was iron. I dunno what else might be in it.
I thought the water would turn blue. It turned rusty brown. So I'm calling it the Messed-up Mystery Mordant, and using it to darken colors.
It stained or you might say dyed my yarn a nice rust orange.
My question is, can I just use it as a dye? Don't bother with a subsequent dye bath, just use it as is, since I like the color? I haven't tried washing it out with soap, but it's been rinsed & seems stable.
Thanks.

Best guess - you may have made "iron buff".  Maybe test it for light-fastness - clip a piece off and fold half of it into doubled or triple folded paper and hang (I pin to the curtains in a sunny window)  I had a particularly nice soft green disappear over 8 days in Autumn sun, so not the strongest ever.
No harm in leaving it as-is if you're happy with it.  Would the US Mint have more info. on the metal contents of coins?  That made me curious - after 1982 US pennies are primarily zinc with a thin copper coat.  Aus. 50c piece is cupro-nickel and that goes green if left out in the weather.
Edit to add - try for a neutral detergent for washing - alkaline ones can damage wool fibres, and also alter the colour.