Is it possible to engrave on a mirror
I’d say you’ll need to cover with tape. And then search the forum for the right settings so you don’t waste material on testing. But yes, engraving/etching can be done on lots of material!
You can also engrave the front or back of glass mirrors. The effect is very different depending on which you choose.
There are a couple techniques that folks use to engrave glass.
Here is one of many mirror topics:
If you engrave on the front you’ll get a reflection of your design - so it’ll look doubled from most angles - one floating on the top, and one beneath
If you engrave from the back there will only be one image and it’ll look like it’s beneath the mirror
Both effects can be very cool - but some work better than others depending on your design
This effect will be more or less pronounced depending on the thickness of the glass. It can range from thick (like 1/4” thick glass) to zero (as in first surface mirrors, which you are unlikely to have).
Go try things out and have fun
It is an interesting effect either way, and I’ve done both front and back of mirrors.