River iron sand

…Iron minerals, which make up 1-2% of igneous rocks, are separated by the weathering of rocks and either concentrate somewhat locally or are transported and accumulated by rivers and other bodies of water. The former are called mountain iron sand, and the latter, depending on where they are accumulated, are called river iron sand, coastal iron sand, or seabed iron sand. Iron sand is mainly composed of magnetite with small amounts of ilmenite and hematite, but the one that is mainly composed of ilmenite is specifically called titanium iron sand. …

*Some of the terminology that refers to "river iron sand" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…火成岩中に1～2％含まれている鉄鉱物が，岩石の風化によって分離し，現地で多少濃集するか，もしくは河川などによって運ばれ集積したものをいう。前者を山砂鉄，後者を集積した場所によって川砂鉄，海岸砂鉄，海底砂鉄と呼ぶ。砂鉄は主として磁鉄鉱からなり，少量のチタン鉄鉱，赤鉄鉱を含むが，主としてチタン鉄鉱からなるものはとくにチタン砂鉄と呼ばれる。…

※「川砂鉄」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報