I had an experience that involved some gorgeous drip-glaze ceramic pots in 4 size sets I discovered at a Big Lots Stire. Sizes in the set ranged from about a quart in volume to maybe 2 gallons. I bought 10 sets (40 pots) on behalf of the San Toshi Bonsai Society in early spring. We also purchased 3 boxes (60 plants) of assorted dwarf conifers from Iseli Nursery, located in Oregon. We drilled holes in the bottom of the pots and transplanted the plants into the pots using the gritty mix so they would be well established in June for our fund-raiser sale at a local art fair. We had single and multi-plant plantings, as you would think would be the case if we had to fit 60 plants into 40 pots. The plants were well-established by the time of the art fair and were a hit with the patrons in spite of the fairly significant outlay. As I remember, we had about 4 plantings of various sizes that didn't sell. I took those home and put them on my grow benches to tend/prune them so we could sell them the following summer. Unfortunately, by August the plants I was tending were all in decline, the ceramic glaze on the pots had begun to craze, and at each of the cracks in the crazing pattern there was a growth of 'something' that looked exactly like the OP showed in the image (s)he provided. Since I had about 150 other conifers covering at least 20 species on the grow bench right next to the struggling plants, it didn't seem appropriate to assign the cause of the decline, which BTW ended in the death of the plants, to grower error - unless you consider choosing pots made with toxic materials to be my error. I have no problem accepting that responsibility, even though I had no reason to suspect that bowls meant to serve as a vessels to hold food for human consumption would be made with toxic ingredients that could be expected to leach into the bowls' contents. The bowls were made in China. While I can't witness with any certainty in the case at hand, I do strongly believe that in the case of the bowls I unfortunately discovered, one or more of the ingredients that were mixed together and formed into bowls before firing were, at a minimum, phytotoxic (poisonous to plants) and at the root of the weird formations that formed at the cracks in the bowls' finish. Remember, because of the soils I use and my watering habits, a build-up of dissolved solids in the soil is dubious in the extreme as causal of the growth formations I saw. Finally, as I remember, I had a strong sense these 'formations' were not organic in nature and were the outgrowth of the chemical formations formed that water as it evaporated left behind. Al

Fungus isn't crystal-like. Is it on the stems close to the soil? That usually means overfertilization, which is common in potted plants. Tibouchina may have gotten root rot. Did you wash the roots off thoroughly and dust them with fungicide before you repotted it? The rot is in the soil, so if you put the garden soil into the pot, it's just going to go on killing it. Here's what I do: Wash the roots off thoroughly Remove as many dead roots as you can. Soak the roots in a water/peroxide mixture overnight to kill the fungus and oxygenate the plant. I put about 8 ozs of peroxide for every 2 gallons of water. Dust the roots with fungicide (rooting hormone or cinnamon will do - yes, the spice cinnamon. Replant in a mixture of 3 parts clean potting soil and 1 part perlite. DO NOT FERTILIZE. Keep the soil moist, but not wet. Stick your finger into the soil up to your second knuckle. If it's dry that far down, water it. If not, leave it.

Can you get a close up of the white and brown spots? It looks like mealy bugs and possibly scale to me but I am not an expert at all.

They look like scale or another related insect that comes in fizzy/waxy species. Doesn't matter too much what exactly they are--for houseplants it's probably best to just scrape them off whenever you see them and hope you get enough to stop the lifecycle. If the plants can take it, putting them in the sink and washing while wiping is even better. Of course if they are really big or delicate plants it might not be as practical. I suspect any insecticide or insecticidal soap you can find for scale (or adelgid or aphids or other sucking insects) would work.