石炭

1. Origins, structure, and basic meaning

• Structure: 石炭, read せきたん, is the mass noun coal.
• Basic usage: 石炭を燃やす uses coal as locomotive fuel; 石炭の標本 presents a sample of the material.

2. Common pitfalls and similar expressions

• Coal as fuel and specimen
  • 石炭 is a fossil fuel formed from ancient plant matter. It is burned for energy, but a physical piece can also be handled as a geological or industrial specimen.