金属

1. Origins, structure, and basic meaning

• Structure: The material-category noun 金属 (きんぞく) broadly denotes metals such as iron and copper.
• Basic usage: It marks material in 金属の板 and can stand as a category contrasted with wood or other materials.

2. Common pitfalls and similar expressions

• A category of material
  • It broadly names a class of materials rather than one particular object.