Labradorite is a plagioclase feldspar, intermediate between albite and anorthite.
In thin section, plagioclase feldspar grains often look like they’re sprinkled with dirt (PPL) or tiny confetti (XPL). You can find the explanation on the plagioclase feldspar page.
| Chemical formula | (Ca,Na)(Al,Si)4O8 |
| Class | Tectosilicate |
| Crystal system | Triclinic |
| Habit | Tabular Massive |
| Color | White Gray Light blue Light green Pale orange-red Black |
| Hardness | 6-6.5 |
| Specific gravity | 2.69 |
| Cleavage/fracture | Perfect on {001}, good on {010}/ Uneven/conchoidal |
| Luster | Vitreous |
| Transparency | Translucent to transparent |
| Streak | White |
| δ | 0.008 |
| PPL | Colorless |
| XPL | First order grays |
| Twinning | Albite Pericline Carlsbad Baveno Manebach |
| Special properties | Labradorescence |
| after minerals.net |
Labradorite in Hand Sample
Labradorite in Thin Section
Labradorite, plane polars
Labradorite in plane polarized light. Click here for crossed polars: Magnification: 40x
Labradorite, crossed polars
Labradorite in cross polarized light. Click here for plane polars: https://youtu.be/Hi8HyFbLdz0 Magnification: 40x