We found this rock in field, it is blue/dark blue and around it has 1 cm wide zone where it is like melted, it is 20 cm long, 1 7cm high and 15 cm long, it is almost a square shape, it was found in Latvia so it can't be volcanic rock.
closed as off-topic by Jan Doggen, Leukocyte, Fred, Erik, gansub Aug 29 at 10:30
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Questions about rock identification requests are off-topic. For more information, see the announcement on meta." – Jan Doggen, Leukocyte, Fred, Erik, gansub
Scale and hardness will make it easier and more detailed, but it looks like scoria, with a rather nice crusting effect.
You might also consider industrial sources, some smelting slag can look like scoria because it is produced in the same way molten minerals mixed with gas.