Stilbite

Part of speech: noun

Definitions

1. A white or colorless zeolite mineral that forms in cavities of basaltic rock and has a pearly luster when split
2. A hydrated silicate of calcium, sodium and aluminium that crystallizes in sheaf-like clusters within volcanic rock
3. A soft zeolite mineral found filling gas bubbles in lava, prized by collectors for its pearly sheen and crystal forms

Etymology: Stilbite is a mineral name built from the Greek "stílbō," meaning "to shine" or "glitter," and the suffix "-ite," which mineralogists have long used to name rocks and minerals. The name points to the mineral's glassy, pearly luster, which catches the light on the surfaces of its crystals. The Greek root sits behind a whole family of scientific words. The same "stilb-" element appears in "stilbestrol" and in "stilbene," a hydrocarbon named for its shine, so a single Greek verb for glittering has been pressed into service across chemistry and mineralogy. Nothing about the word is hidden in its construction: a Greek adjective for shining plus the standard mineral ending gives a name that describes what the stone looks like.