This is an automated archive.

The original was posted on /r/askscience by /u/Academic_Appeal735 on 2023-08-05 05:28:09+00:00.

Title pretty much says it all. A little back story, my sister went to Amsterdam a couple months ago and got me some little phosphorus/quartz crystals. I noticed they glow in the dark at night after I turn off my lamp so I was wondering what causes that to happen?