olivine

noun

1. (countable, uncountable)Any of a group of olive green magnesium-iron silicate minerals that crystallize in the orthorhombic system.

   “The olivine crystals in most basalts are imperfect, lacking clear crystal faces.”

   “To do so, his team mixed together limestone with a crushed silicate mineral that contains magnesium — such as olivine, an olive-tinted mineral that can be found around the world. When heated to furiously high temperatures in a kiln, calcium in the limestone and magnesium in the silicate jiggle and switch sides, like participants in a square dance.”