Maintenance for the week of November 18:
• PC/Mac: No maintenance – November 18
• ESO Store and Account System for maintenance – November 19, 9:00AM EST (14:00 UTC) - 6:00PM EST (23:00 UTC)
• PlayStation®: EU megaserver for maintenance – November 19, 23:00 UTC (6:00PM EST) - November 20, 17:00 UTC (12:00PM EST) https://forums.elderscrollsonline.com/en/discussion/668861
I noticed a lot of them like to hang out near lore book locations.
Since they nerfed the spawn rates, it is much harder to find an active one, and likely not worth the effort to farm. But they are still highly noticeable thanks to their bright bluish glow. During a night cycle get on your mount and ride off trail all over the map. Make note of any you find. Each time you take one a new one will spawn, so you'll need to cover the map several times. This is more work, but it's better this way because you will learn where the least trafficked spots are that give you a better chance of snagging a trove.
Like the poster above suggested, farming them at night (if you intend to farm them at all) is probably best. They are super easy to spot at night.
I've noticed they've also appeared for me several times underneath dock areas. You might want to start you search going along the coastlines of some areas and check all around the docks and piers (especially underneath them).