Looks like dust to me, but if OP can snap a pic of the under side of a leaf it would be easier to tell. Calathea's are definitely a common treat for mites.
I highly recommend a pocket magnifier like This one for home identification.
That one should work just fine!! The little ones like that are much easier to maneuver. Personally I use an adjustable handheld microscope. The link for my favorite is at the bottom. I also have a few that have more magnification, and one that I can plug into my Chromebook. The only one that's absolutely necessary is anything that lets you see the trichs. Everything else is just because they're fun and I'm a nerd about it lol
https://www.amazon.com/dp/B077TLGP58?ref=ppx_pop_mob_ap_share
I bought one of those digital scopes and I had a real hard time getting a decent image out of it. Eventually I gave up and just went with this 20x-60x pocket microscope for like $15 and I find it much easier to use. I can't save images with it but it works for me.
Carson Pocket Micro 20x-60x LED Lighted Zoom Field Microscope with Aspheric Lens System (MM-450),Blue https://www.amazon.com/dp/B077TLGP58/ref=cm_sw_r_cp_apan_glt_fabc_MSCNCBH84EQF7HC739GE?_encoding=UTF8&psc=1
Hi this is the one i got, from amazon. I like it because i can look right on my arm with the microscope, i dont have to scrape it and put it on a slide or anything like that. It's also pretty sturdy. But someone else said they had the same one as me and they have a hard time with it. I can see very clearly through mine though
Apparently this is my day to make this post... Copy/pasted from another post today.
Get a pocket microscope! Like this One. You will never see them otherwise. They mostly hang out on the underside, as well as where the leaf and stem meet. Check at least monthly.
If you suspect or find mites, quarantine and cut worst of the leafs off. Rinse leafs well. Then mix up a bottle of rubbing alcohol (about a quarter of the way up) a very healthy squert of dawn (no subbing here), and warm water. Shake up. Spray plant down and wipe with stiff blush brush (or something similar). Follow the natural pattern of the leaf with the brush. Get both side well, rewet as needed. Treat 2-3 a week until mites are gone, then monthly for a few.
Also, add some diatomaceous earth (DE) to the soil to kill any mites/eggs in there.
Make sure you have a good amount of room between this guy and other plants for a few weeks at least. I refuse to buy clatheas anymore, too many bug problems. I had a white fusion calathra for over a year, checked it regularly, not problems. It was a happy little guy. It wasn't anywhere near other plants, then, bam! Spider mites showed up.
So what to do?
Get a pocket microscope! Like this One. You will never see them otherwise. They mostly hang out on the underside, as well as where the leaf and stem meet. Check at least monthly.
If you suspect or find mites, quarantine and cut worst of the leafs off. Then mix up a bottle of rubbing alcohol (about a quarter of the way up) a very healthy squert of dawn (no subbing here), and warm water. Shake up. Spray plant down and wipe with stiff blush brush (or something similar). Follow the natural pattern of the leaf with the brush. Get both side well, rewet as needed. Treat bi-weekly until mites are gone, then monthly for a few. Good luck!
I just have trouble focusing on different parts of the plant cuz of my fan and I'm treating my buds like they're made of glass lol
Do you clip samples then check?
Run search on Amazon......The have some that will interface with your phone and or computer, now that would be real handy . Here is one like mine that I bought 30 years ago.....https://www.amazon.com/Carson-20x-60x-Microscope-Aspheric-MM-450/dp/B077TLGP58/ref=sr_1_5?dchild=1&keywords=handheld+microscope&qid=1601119971&sr=8-5
You need a microscope but even that won't tell you the entire story, only consuming it will tell you that :) Turns out thc is contained in the memranes as well as the resin, maybe even more than in the resin, so even if you don't only have the globular heads you still may have great keif. Press it! hehe Nice keif :)
These are microscopes I use(20x-60x and a 60x-120x; the 20x-60x is more than enough for examining keif):
https://www.amazon.ca/gp/product/B077TLGP58/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://www.amazon.ca/gp/product/B00LAX52IQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I have this one. I can easily do the green dot test and can tell whether the glue is blue or not. It's worked quite well for me.
I found links in your comment that were not hyperlinked:
I did the honors for you.
^delete ^| ^information ^| ^<3