Emily Dickinson Lexicon

FLINT, n. [Sax. flint; Sw. flinta. In Dan. flint is a light gun, and flint is called flintsteen, flint-stone. So also in German. The Dutch and Germans call it also firestone. It may be from the root of splendor.]

1. In natural history, a sub-species of quartz, of a yellowish or bluish gray, or grayish black color. It is amorphous, interspersed in other stones, or in nodules or rounded lumps. Its surface is generally uneven, and covered with a rind or crust, either calcarious or argillaceous. It is very hard, strikes fire with steel, and is an ingredient in glass. Kirwan. Encyc.
2. A piece of the above described stone used in firearms to strike fire.
3. Any thing proverbially hard; as a heart of flint. Spenser.