Research / Geoscience / Language

Bytownite

A calcium-rich plagioclase compositional variety between labradorite and anorthite.

Language and route: English mineralogical place-name formation. English bytownite from Bytown, the former name of Ottawa, Canada

Literal gloss: from Bytown (Ottawa)

The name and its history

Thomas Thomson · 1835 (reported by 1911 Britannica; first printing requires check)

What does the word literally mean?: The gloss ‘from Bytown (Ottawa)’ describes the linguistic allusion. The original name and its modern scientific definition must be kept distinct.
What did the original author mean?: Thomson named an apparently feldspathic mineral from a boulder near Bytown, the predecessor town of Ottawa.
Why was the name needed?: A distinctive Canadian feldspathic specimen needed identification and classification.
What evidence supported the original concept?: Visible and chemical characteristics of the reported specimen; later optical microscopy contradicted the assumption of a single mineral.
How has geology changed the concept?: The original material was later recognised as a mixture. The name survived as a Ca-rich plagioclase compositional interval defined by chemistry, not the original Bytown specimen.

The 1911 Encyclopaedia Britannica explicitly describes both the original locality and the historical failure of the original mineral assignment.

Encyclopaedia Britannica (1911), Bytownite — Historical naming and later reinterpretation
Mindat, Bytownite — Modern composition and historical specimen caveat