A rock containing enough iron to permit commercial extraction; an iron ore.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "ironstone" in a sentence
"In semiarid and subhumid areas with acidic soils a rock-like layer called ironstone can form (Box 9.4)."
"These soils tend to have low levels of plant nutrients, harden irreversibly when exposed to repeated cycles of wetting and drying, and form nodules or rock-like layers called ironstone or laterite."
"Much good has hence resulted; many subordinate improvements have been effected and are almost daily making; and a new variety of ware, called ironstone, has been invented, and so rapidly and judiciously improved, that, in appearance and in many of its intrinsic properties, it bears a close resemblance to the older and coarser porcelains of China itself."