Longer exposures help, but a wider lens can also make those short trails look more dramatic.

Lost the connection" seems a bit dramatic. Couldn't you just plug back in after they finished cleaning?

My cousin bought a whole bucket of "obsidian" at a flea market last year, turned out to be 100% industrial slag. The real giveaway is that conchoidal fracture, it looks like broken glass with those curved ripples. Slag just looks chunky and wrong, like someone melted a bunch of junk together. I always tell people if it looks like it came from a factory and not a volcano, you probably have a nice piece of trash.

Tbh the "life or death choice" part is exactly why these debates feel so silly.

My neighbor did the same thing with gravel and had the exact same problem! He ended up adding a few native shrubs and some mulch paths, and he said it made a noticeable difference in how hot his patio felt. It's crazy how much those rocks can bake in the sun. Your point about the rain washing everything out is so true, I've seen that happen on my street too. It really seems like a few plants for shade and roots to hold the soil are worth the extra cost upfront.