Albitite is a rare igneous rock composed almost entirely of albite (NaAlSi₃O₈), the sodium-rich feldspar. It is essentially a leucocratic (light-colored) granite-like rock, but distinguished by its overwhelming dominance of albite over other feldspars.
🌍 Origins and Naming
- Name Origin: Derived from albite, the principal mineral.
- Type: A rock name, not a mineral species.
- Classification: Felsic intrusive rock, part of the granite family but unusually sodic.
🔬 Composition and Properties
- Main Mineral: Albite (NaAlSi₃O₈) — typically >90% of the rock.
- Accessory Minerals: Quartz, muscovite, biotite, tourmaline, garnet, and occasionally rare-element minerals.
- Color: White, pale gray, or pinkish due to albite dominance.
- Texture: Coarse-grained, equigranular, massive.
- Structure: Intrusive, often forming dikes or small plutons.
⚙️ Geological Occurrence
- Found in granitic intrusions and pegmatite complexes.
- Often associated with rare-element mineralization (uranium, niobium, tantalum, lithium).
- Localities:
- Namibia (Rossing uranium mine, where albitite hosts uranium ore).
- Canada, Russia, and other regions with rare-element pegmatites.
📖 Scientific and Economic Significance
- Petrology: Important for understanding extreme sodic differentiation in granitic magmas.
- Economic Note:
- Albitite can host uranium deposits (Rossing mine, Namibia).
- May also contain rare-element minerals, making it of interest in economic geology.
- Collectors: Not a collector’s rock, but specimens are valued academically.
✨ Conclusion
Albitite is a sodium-rich granite-like rock, composed almost entirely of albite, found in specialized granitic intrusions. Though visually modest, it is geologically significant and economically important as a host rock for uranium and rare-element mineralization.
In short: Albitite = albite-rich granite, intrusive felsic rock, linked to uranium deposits (e.g., Rossing mine, Namibia).
