apophyllite Min.
(əˈpɒfɪlaɪt, æpəʊˈfɪlaɪt)
[mod. f. Gr. ἀπό off + ϕύλλον leaf + -ite; ‘so named by Haüy, 1805, in allusion to its tendency to exfoliate under the blow-pipe’ (Dana).]
A zeolitic mineral, a hydrated silicate of lime and potash, with a trace of fluorine; occurring in glassy square prisms or octahedrons, or laminated masses, with a pearly lustre; widely distributed in nature, and produced artificially.
| 1810 Edin. Rev. XVII. 119 The sparry lustre which characterizes apophyllite. 1878 Lawrence Cotta's Rocks Class. 26 Apophyllite is found in the geodic cavities of volcanic rocks. |