Anhydrites

Part of speech: noun

Definitions

1. A type of mineral composed of anhydrous calcium sulfate, typically occurring in sedimentary rocks
2. A non-water-containing form of calcium sulfate that appears in evaporite deposits within geological formations
3. A mineral characterized by a lack of water molecules in its crystal structure, often found in various geological environments

Etymology: Anhydrite is a mineral, and the name is a compound built from Greek pieces that literally mean "without water." The "an-" is the Greek negative prefix, the same one found in words like "anarchy," and "hydro-" comes from Greek "hudor," meaning water. The suffix "-ite," which English uses to name minerals and rocks, descends from a Greek ending that Latin later borrowed and French passed on to English. The name points to the mineral's chemistry. Anhydrite is calcium sulfate, the same compound as gypsum but without the water molecules bound into its crystal structure. Gypsum contains two water molecules per formula unit, and anhydrite is what remains when those are absent, so the name describes exactly what is missing. "Anhydrites" is simply the plural of "anhydrite," used when referring to several specimens or deposits of the mineral.