Opal
At a glance
- Type
- Mineraloid
- Group
- Oxide
- Crystal system
- Amorphous
- Hardness
- Hard (5.5 to 7.5)
- Colour
- White, Green, Blue
- Lustre
- Glassy, Resinous
- Use
- Gemstone
- Difficulty in WildGuessr
- Medium
Did you know?
- Opal is made of tiny silica spheres that split light into flashes of colour.
- Opal holds up to about 20 percent water, so it can crack if it dries out too fast.
Could you guess it from clues?
WildGuessr picks a secret animal, plant, fungus, stone, prehistoric creature or space object and you ask yes-or-no questions about it, such as its group or where it grows. The fewer clues you need, the more points you score.
Similar stones
Classification, names and conservation status come from Wikidata (CC0), the photo from Wikimedia Commons. Wikidata Q171058 · All stones · All entries