Weird Words: Conchoidal
Conchoidal is not only a weird geological term, it is also vitally important in terms of developments that led to human survival. In geology, conchoidal refers to a curved, shell-like shape that certain brittle rocks and minerals exhibit if fractured by a blow. As a result of the radiating shock created by a sharp blow, such fractures have smooth rounded concentric ridges that resemble a mussel shell with its growth lines. Indeed, the word “conchoidal” is derived from the Greek word konkhoeides, meaning “like a mussel”.
Conchoidal fracture in obsidian enabled stone-age cultures to produce arrowheads.