from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A substance that resembles a mineral but does not exhibit crystallinity.
Sorry, no etymologies found.
Obsidian is sometimes classified as a mineraloid, however its composition is too complex to be a single mineral.
Interestingly, it is a mineraloid gel which is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock.