Input interpretation
labradorite (mineral)
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General properties
alternate names | black moonstone | carnatite | labrador feldspar | labrador moonstone | mauilite | opaline feldspar | radauite | silicite | spectrolite formula | (Ca, Na)(Si, Al)_4O_8
Basic properties
density | 2.695 g/cm^3 transparency | translucent | transparent birefringence | 0.009 luster | subvitreous Mohs hardness | 6.25 streak | white magnetism | nonmagnetic color | colorless | gray | gray white | white | light green fracture | uneven molar mass | 271.8 g/mol (grams per mole)
Units
Mineral identifiers
Strunz ID | VIII/J.07-50 Dana ID | 76.1.3.4
Crystallographic properties
crystal system | triclinic crystal class | 1 unit cell volume | 952.2 Å^3 (cubic ångströms) d-spacing | 3.18 Å (ångströms) | 3.21 Å (ångströms) | 3.76 Å (ångströms) intensity | 100% | 70% | 70% molecules per unit cell | 6 molecules per cell 2V angle | 41 π/90 radians≈82° (degrees) refractive indices | 1.559 | 1.563 | 1.568 | 0 | 0 | 0 dispersion | none unit cell lengths | 8.155 Å (ångströms) | 12.84 Å (ångströms) | 10.16 Å (ångströms) unit cell angles | 93.5° (degrees) | 116.3° (degrees) | 89.13° (degrees)
Wikipedia summary
Labradorite ((Ca, Na)(Al, Si)_4O_8), a feldspar mineral, is an intermediate to calcic member of the plagioclase series. It has an anorthite percentage (%An) of between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573 and twinning is common. As with all plagioclase members, the crystal system is triclinic, and three directions of cleavage are present, two of which are nearly at right angles and are more obvious, being of good to perfect quality. (The third direction is poor.) It occurs as clear, white to gray, blocky to lath shaped grains in common mafic igneous rocks such as basalt and gabbro, as well as in anorthosites.