Coal
At a glance
- Type
- Rock
- Group
- Sedimentary rock
- Crystal system
- None (a rock)
- Hardness
- Soft (Mohs under 3)
- Colour
- Black, Brown
- Lustre
- Glassy, Dull
- Use
- Fuel
- Difficulty in WildGuessr
- Easy
Did you know?
- The Carboniferous period, over 300 million years ago, means coal-bearing; its swamp forests became much of our coal.
- Buried peat turns step by step into brown coal, then hard coal, and finally anthracite.
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 Q24489 · All stones · All entries