\Sid"er*ite\, n. [L. sideritis loadstone, Gr. ????,
????, of iron, from ???? iron.]
1. (Min.)
   (a) Carbonate of iron, an important ore of iron occuring
       generally in cleavable masses, but also in
       rhombohedral crystals. It is of a light yellowish
       brown color. Called also {sparry iron}, {spathic
       iron}.
   (b) A meteorite consisting solely of metallic iron.
   (c) An indigo-blue variety of quartz.
   (d) Formerly, magnetic iron ore, or loadstone.
2. (Bot.) Any plant of the genus {Sideritis}; ironwort.