Bytownite is a calcium rich member of the plagioclase solid solution series of feldspar minerals with composition between anorthite and labradorite. It is usually defined as having between 70 and 90%An (formula: (Ca0.7−0.9Na0.3−0.1)[Al(Al,Si)Si2O8]). Like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations.
The specific gravity of bytownite varies between 2.74 and 2.75. The refractive indices ranges are nα=1.563 – 1.572, nβ=1.568 – 1.578, and nγ=1.573 – 1.583. Precise determination of these two properties with chemical, X-ray diffraction, or petrographic analysis are required for identification.
Bytownite is a calcium rich member of the plagioclase solid solution series of feldspar minerals with composition between anorthite and labradorite. It...
member (albite 2.62) increases 0.02 per 10% increase in anorthite (2.75). Bytownite, named after the former name for Ottawa, Ontario, Canada—Bytown— is a...
certain composition; those of calcic labradorite (50–70% anorthite) and bytownite (formula: (Ca0.7-0.9,Na0.3-0.1)[Al(Al,Si)Si2O8], i.e., with an anorthite...
gaps in phase systems are named, including The huttenlocher (found in bytownite, anorthite composition An55-95.), boggild (in labradorite, An39-48 and...
from sodium- to calcium-rich): oligoclase, andesine, labradorite, and bytownite. Other examples of series include the olivine series of magnesium-rich...
much silica and alkalis. In the mafic rocks labradorite, anorthite, and bytownite prevail, being rich in lime and poor in silica, potash, and soda. Augite...
dating back to the Bytown era. The name Bytown survives in the name of Bytownite, a calcium-rich plagioclase feldspar mineral, named from its occurrence...
relatively large grain size. Eucrite is also a now obsolete term for bytownite-gabbro, an igneous rock formed in the Earth's crust. The term was used...
pyroxene. The feldspar is a basic variety of plagioclase (anorthite or bytownite). Though mostly rounded, the spheroids may be elliptical or subangular;...
simulants, the NU-LHT (lunar highlands type) series and OB-1 (olivine-bytownite) were developed and produced in anticipation of the Constellation activities...
trachybasaltic. These are black rocks and contain small augite, anorthite (bytownite and labradorite types) and olivine phenocrysts. This first cone is lengthened...
pyroxene (mostly orthopyroxene with exsolved augite) and plagioclase (mostly bytownite and anorthite) with small amounts of chromite, ilmenite, pigeonite, tridymite...
Assoc. 1: 33–36. Wenk, E.; Wenk, H.-R.; Schwander, H. (1 October 1968). "Bytownite from Cape Parry, East Greenland". American Mineralogist. 53 (9–10): 1759–1764...
is always idiomorphic with rounded outlines. The feldspar ranges from bytownite to oligoclase, being usually a variety of labradorite; orthoclase is scarce...
with variable amounts of vesicles. Minerals found in the rocks include bytownite, clinopyroxene, iron-titanium oxides, labradorite, orthopyroxene and plagioclase...
Global Information