Macerals

Part of speech: noun

Definitions

1. Microscopically distinct organic components that make up coal, identifiable by their optical properties under a microscope
2. Individual organic materials visible in coal under magnification, such as vitrinite or inertinite, that combine to form the rock
3. Microscopic organic phases within coal that can be differentiated by their reflectance and other optical characteristics

Etymology: Marie Stopes, better known today for her work on birth control, was also a paleontologist, and in 1935 she coined this word while writing about the layered structure of bituminous coal. She proposed it in an article on the petrology of banded coal, explaining that she wanted a term that would sit alongside "mineral" in a tidy pairing. Her chosen model was the Latin "macerare," meaning "to macerate," or to soften and break something down by soaking it. The choice was deliberate and apt. Stopes argued that coal, whatever its original nature, consists of macerated fragments of vegetation that accumulated under water, so a word built on "macerate" described what coal physically is. The ending "-al" follows the pattern of "mineral," which is why the new term looks and sounds like a familiar scientific word even though it was made only in the 1930s.