Blaah! It sure looks like scale to me. If you can easily scrape it off with a fingernail (or something more hygienic, LOL), then that would be my guess.

If it was my plant I'd just rip it out and discard it and trim off the affected parts of your mint, and then use a cotton ball with 70% rubbing alcohol to swap down the rest of your mint (don't do it during times when direct sun is shining on the mint), and then keep an eye open for stragglers. Repeat every week or so until you don't see any more.

If it gets out of hand you can always get insecticides (organic or otherwise), but rubbing alcohol and vigilance are a good start.

Let's see what the other folks say, but I'd rip it out ASAP so it doesn't act as a reservoir for scale to continue spreading.

Let us know what you do and how it works out. Excellent job with the pics, by the way, I really struggle to get closeups as nicely focused as yours.

Take care,
Grant

Cheers Grant :) I apologise for the graphics! It's been a long time since I've seen scale and wanted a verification before I acted.

We have a very industrious colony of ants nearby and the scale seems to be everywhere now. Last month it was aphids, I used a dish soap/garlic/pepper solution. I'll report my findings.

The shots are an older Panasonic/Lumix FZ5, close-ups are iffy unless the light is very good. Unfortunately these shots of scale are some of the best I've taken :/

All the best!

LOL, that's funny about the close ups! Keep us posted on your treatments and how they work. Safer's Insecticidal soap is pretty good, and the Bayer Systemic is fantastic, but very, very toxic for 30 days (not for any food plant). Hopefully your planned treatment will work.

Keep us posted. I'm sure I'm not the only one who is curious.

Take care and good luck!
Grant

While not conclusive it is convenient to post my progress now :)

I use powdered hot pepper (cayenne I think) and a few buds of minced garlic soaked in isopropyl, strained and mixed with dish soap, applied with an atomizer. Same recipe I used for the aphids, the plants don't seem to mind it. Various sources recommend the same for scale.

I have only applied this once since posting, the mint looks better as the scale had not taken over much. Having removed problem spots I'm not sure there is any scale left on it at present. No progress on the snaps (I'm waiting for the second batch to soak).

I also started watering the foliage of the mint.. I've habitually avoided this to minimise calcium spotting on the leaves and to encourage root growth. Changing this habit took care of the few white flies that were enjoying the mint.

Since the snap is fairly extreme, if it pulls through I'll bump the thread again :)