taconite

A variety of chert containing magnetite and hematite, mined as an iron ore.

In petrography, a name proposed by H. V. Winchell (1896) for cherty or jaspery rock, in places calcareous or quartzitic, associated with the hematites of the Masaba Range, Minnesota.

a low-grade flint–like iron ore containing 20-30% iron

a variety of chert containing magnetite and hematite; mined as a low-grade iron ore