1) Chert 2) Iron mineral 3) Iron ore 4) Mined as a low-grade iron ore 1) Iron ore 2) Ore 
Taconite is a variety of iron formation, an iron-bearing (> 15% iron) sedimentary rock, in which the iron minerals are interlayered with quartz, chert, or carbonate. Newton Horace Winchell, the Minnesota State Geologist, coined the term during his pioneering investigations of the Precambrian Biwabik Iron Formation of northeastern Minnesota. He not...
a low-grade siliceous iron formation in Minnesota, U.S., from which high-grade iron ore is derived. The iron formation consists of fine-grained ... [1 related articles]
Type of iron ore principally from the US Midwest.
[n] - a variety of chert containing magnetite and hematite
Natural mineral containing less than 30% iron. It is the primary ore used in blast furnaces. Domestic supplies of iron-rich ores (greater than 50% iron) were largely depleted in the 1940s, so integrated steel companies now process the lower-grade taconite to make it useful.
noun a variety of chert containing magnetite and hematite; mined as a low-grade iron ore
A bedded ferruginous chert containing at least 25% iron. A potential iron ore.
A highly abrasive iron ore.
A highly abrasive iron ore.