Ironstone

I'ron·stone` noun A hard, earthy ore of iron. Clay ironstone . See under Clay . -- Ironstone china , a hard white pottery, first made in England during the 18th century.
Found on http://www.encyclo.co.uk/webster/I/96

Ironstone

• (n.) A hard, earthy ore of iron.
Found on http://thinkexist.com/dictionary/meaning/ironstone/

ironstone

(from the article `sedimentary rock`) ...extensive, locally thick sequences composed of alternating thin (millimetre to centimetre thick) layers of mainly crystalline-textured iron-rich ...
Found on http://www.britannica.com/eb/a-z/i/40

Ironstone

Ironstone is a rock containing at least fifteen percent iron. Ironstone forms in igneous rocks through mahmatic differentiation - dense heavy minerals such as magnetite crystallise first and sink to the base of the molten magma to form an iron-rich layer. Ironstone also forms in sedimentary rocks such as limestone and sandstone.
Found on http://www.probertencyclopaedia.com/browse/HI.HTM

Ironstone

Ironstone is a sedimentary rock, either deposited directly as a ferruginous sediment or created by chemical replacement, that contains a substantial proportion of an iron compound from which iron either can be or once was smelted commercially. This term is customarily restricted to hard coarsely banded, nonbanded, and noncherty sedimentary rocks o...
Found on http://en.wikipedia.org/wiki/Ironstone

ironstone

the name given to various hard iron-ores containing admixtures of silica, clay, etc
Found on http://florabase.dpaw.wa.gov.au/help/glossary

Ironstone

A mudstone or sandstone with a high iron content.
Found on http://www.bgs.ac.uk/discoveringGeology/glossary.html
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