Input interpretation
bytownite (mineral) | fluorannite (mineral)
Images
Images
General properties
| bytownite | fluorannite alternate names | ab20 | plagioclase (An70-90) | (none) formula | (Ca, Na)(Si, Al)_4O_8 | KFe^(2+)_3AlSi_3O_10F_2
Basic properties
| bytownite | fluorannite density | 2.71 g/cm^3 | 3.175 g/cm^3 transparency | translucent | transparent | translucent birefringence | 0.0105 | 0.052 luster | subvitreous | submetallic Mohs hardness | 6.25 | 3 streak | white | gray magnetism | nonmagnetic | nonmagnetic color | colorless | gray | white | iron black fracture | uneven | sectile molar mass | 275 g/mol | 473.8 g/mol
Units
Mineral identifiers
| bytownite | fluorannite Strunz ID | VIII/J.07-60 | VIII/H.11-105 Dana ID | 76.1.3.5 | 71.2.2b.3a IMA number | | IMA1999-048
Crystallographic properties
| bytownite | fluorannite crystal system | triclinic | monoclinic crystal class | 1 | 2/m unit cell volume | 1239 Å^3 (cubic ångströms) | 498 Å^3 (cubic ångströms) d-spacing | 3.2 Å (ångströms) | 3.75 Å (ångströms) | 4.03 Å (ångströms) | 10.09 Å (ångströms) | 3.336 Å (ångströms) | 5.02 Å (ångströms) | 1.671 Å (ångströms) | 2.004 Å (ångströms) | 2.507 Å (ångströms) | 2.649 Å (ångströms) | 2.933 Å (ångströms) | 3.16 Å (ångströms) intensity | 100% | 80% | 80% | 100% | 56% | 13% | 10% | 10% | 10% | 10% | 10% | 10% molecules per unit cell | 7 molecules per cell | 2 molecules per cell 2V angle | 7 π/15 radians≈84° (degrees) | refractive indices | 1.568 | 1.573 | 1.578 | 0 | 0 | 0 | 1.596 | 0 | 0 | 0 | 0 | 0 dispersion | r > v | strong | r < v | weak unit cell lengths | 8.17 Å (ångströms) | 12.85 Å (ångströms) | 13.16 Å (ångströms) | 5.37 Å (ångströms) | 9.289 Å (ångströms) | 10.15 Å (ångströms) unit cell angles | 93.5° (degrees) | 116° (degrees) | 90.83° (degrees) | 90° (degrees) | 100.5° (degrees) | 90° (degrees)
Wikipedia summary
Bytownite
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: (Ca_(0.7-0.9), Na_(0.3-0.1))). Like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations.