Editing Iron ore (section)

=== Banded iron formations ===
{{Main|Banded iron formation}}
[[File:Black-band ironstone (aka).jpg|thumb|Banded iron rock, estimated at being 2.1 billion years old]]
[[File:TaconitePellet.JPG|thumb|Processed [[taconite]] pellets with reddish surface oxidation used in [[steelmaking]] with a [[Quarter (United States coin)|U.S. quarter]] (diameter: {{Convert|24|mm|abbr=on|disp=sqbr}}) shown for scale]]
[[Banded iron formation]]s (BIFs) are [[sedimentary rock]]s containing more than 15% iron composed predominantly of thinly-bedded iron minerals and [[silica]] (as [[quartz]]). Banded iron formations occur exclusively in [[Precambrian]] rocks, and are commonly weakly-to-intensely [[Metamorphism|metamorphosed]]. Banded iron formations may contain iron in [[Carbonate mineral|carbonates]] ([[siderite]] or [[ankerite]]) or [[Silicate mineral|silicates]] ([[minnesotaite]], [[greenalite]], or [[grunerite]]), but in those mined as iron ores, [[Oxide mineral|oxides]] ([[magnetite]] or [[hematite]]) are the principal iron mineral.<ref>Harry Klemic, Harold L. James, and G. Donald Eberlein, (1973) "Iron," in ''United States Mineral Resources'', US Geological Survey, Professional Paper 820, p.298-299.</ref> Banded iron formations are known as ''[[taconite]]'' within North America.

The mining involves moving tremendous amounts of ore and waste. The waste comes in two forms: non-ore bedrock in the mine ([[overburden]] or interburden locally known as mullock), and unwanted minerals, which are an intrinsic part of the ore rock itself ([[gangue]]). The mullock is mined and piled in [[Overburden|waste dump]]s, and the gangue is separated during the [[beneficiation]] process and is removed as [[tailings]]. Taconite tailings are mostly the mineral [[quartz]], which is chemically inert. This material is stored in large, regulated water settling ponds.