岩石

1. Origins, structure, and basic meaning

• Structure: 岩石 (がんせき) is a noun for naturally occurring rock material or a type of rock in geology.
• Basic usage: 模様のある岩石を拾う makes an individual patterned rock the object picked up, while 地層を作る岩石の種類 investigates rock categories forming strata.

2. Common pitfalls and similar expressions

• Individual specimen and geological category
  • 岩石を拾う concerns one portable specimen, whereas 岩石の種類 concerns geological material classes forming strata. The second should not be narrowed to classifying only the one riverbank stone.