| In many cases stones lying around or stones in a riverbed are used, however, the stones that could be produced only in the limited place, such as obsidian, shale and sanukite would be not only collected from the ground but also mined. |
転がっている石や河原石を使う場合が多いが、黒曜石や頁岩、サヌカイトなど産地の限られた石材の場合には転石を拾うばかりではなく、採掘もおこなう。 |