Min. [a. Fr. épidote, f. as if on Gr. *ἐπιδοτός, f. ἐπιδιδόναι to superadd, f. ἐπί upon + διδόναι to give.
First used in Fr. by Haūy, who explains it as meaning lit. ‘qui a reçu un accroissement’ (Mineralogie 1801, III. 112), and as denoting a great additional length in the base of the crystal as compared with that of certain allied minerals with which it was previously confused.]
A mineral common in many crystalline rocks, consisting largely of the silicate of iron and lime. It usually takes the form of flattened needles, and has a peculiar yellowish-green color.
1808. T. Allan, Minerals, 2. Akanticone or Thallite, Epidote.
1879. Rutley, Study Rocks, x. 127. Epidote seldom gives direct evidence of its derivation from pyroxenic minerals.
Hence Epidotic a., pertaining to or resembling epidote, containing epidote. Epidotiferous a., bearing or containing epidote.
1849. Dana, Geol. (1850), 565. The granitic and epidotic veins. Ibid. (1862), Man. Geol., 76. An epidotic gneiss.
1884. Harper’s Mag., 159/2. Veins of … epidotiferous quartz.
