[Skyblock] How do you obtain quartz?

On skyblock, I'm trying to make an automated farm and observer blocks would make things much more simpler. After checking the recipe and learning I need quartz, I started to wonder how you could get more quartz. I already mined up my entire nether skyblock and turned the quartz into blocks for a challenge. Also, the shop does not sell quartz. Are there any other way to obtain quartz?