Phacolites

Part of speech: noun

Definitions

1. A zeolite mineral, an aluminosilicate of calcium and sodium that forms lens-shaped twinned crystals, now often grouped with chabazite
2. A hydrated silicate mineral of the zeolite family that typically occurs as flattened, lens-like crystals in volcanic rock cavities
3. Any member of a group of porous aluminium silicate minerals whose lens-shaped crystals are closely related to chabazite

Etymology: "Phacolites" is the plural of "phacolite," a name for a lens-shaped volcanic mineral. The singular comes from Greek "phakós," meaning "lens," which is also the source of the word "lentil," since the lentil plant's seeds are shaped like small lenses. The "-lite" ending comes from Greek "lithos," meaning "stone," and is the standard suffix mineralogists use for rock and mineral names. Mineral names built this way are common: "zeolite," for example, combines Greek "zein," to boil, with "lithos," because the mineral bubbles when heated. The pattern tells you the name is a descriptive coinage, made by mineralogists to describe what the stone looks like rather than to commemorate a person or a place.