bytownite
Sign in to saveBytownite 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: ). Like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations.
Key facts
- Mineral.system
- Triclinic
- Mineral.class
- Pinacoidal ()
- Mineral.symmetry
- P (no. 2)
- Mineral.unit cell
- a = 8.178 Å, b = 12.870 Å, c = 14.187 Å; α = 93:5°, β = 115:9°, γ = 90:63°; Z = 8
- Mineral.color
- Colorless, white, gray
- Mineral.habit
- Rarely as crystals flattened on [010], commonly as cleavable masses or anhedral grains in massive aggregates
- Mineral.twinning
- Common Albite, Carlsbad, and Pericline twinning
- Mineral.name
- Bytownite
- Mineral.category
- Tectosilicate minerals
- Mineral.group
- Feldspar group
- Mineral.series
- Plagioclase feldspar series
- Mineral.image
- Bytownite-mrz296a.jpg
- Mineral.imagesize
- 170px
- Mineral.caption
- A somewhat rounded, alluvial crystal of bytownite from the Dorado Mine, Casas Grandes, Chihuahua, Mexico (size 3.7 × 2 × 1.3 cm)
- Mineral.formula
- (Ca,Na)[Al(Al,Si)Si2O8] (Na:Ca = 10:90 to 30:70)
- Mineral.IMAstatus
- Variety of anorthite
- Mineral.strunz
- 9.FA.35
- Mineral.dana
- 76.01.03.05
via Wikipedia infobox
Article
3 sectionsContents
- Occurrence
- References
- External links
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: {{Chem2|(Ca_{0.7-0.9}Na_{0.3-0.1})[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.