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Variety · Silicate

Bytownite

(Ca,Na)(Al,Si)₄O₈

Anorthite-rich plagioclase, named for Bytown (Ottawa).

Hardness6–6.5
Crystal systemTriclinic
ClassSilicate
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Bytownite specimen

Bytownite is a rare member plagioclase series of the feldspar group. Its chemical formula is (Ca,Na)(Si,Al)4O8. Bytownite by definition must contain 30-10% sodi — Photo: Shannon Heinle · CC0

Bytownite

A calcium-rich plagioclase feldspar sitting between labradorite and anorthite in the solid-solution series.

Intro adapted from Wikipedia (CC BY-SA).

Bytownite is a mineral variety of Anorthite, with the chemical formula (Ca,Na)(Al,Si)₄O₈.

It crystallizes in the triclinic crystal system.

Key properties: Mohs hardness 6–6.5; typically white or gray.

Collections: Collector Favorites.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet. Browse more B minerals or help write this entry.