Albite

Albite is a plagioclase feldspar mineral, a tectosilicate, forming a solid solution series with anorthite. It is the sodium endmember (NaAlSi3O8), distinguished by a high sodium content. albite crystallizes in the triclinic system, typically forming tabular or platy crystals, often with a pearly luster. Its color ranges from colorless or white to pale shades of gray, yellow, or red. It is a common constituent of igneous, metamorphic, and sedimentary rocks, found in granites, pegmatites, gneisses, and sandstones, often associated with other feldspars and quartz. The hardness of albite on the Mohs scale is 6 to 6.5, and the specific gravity is around 2.62.

Albite meaning with examples

• The granite sample contained visible, white albite crystals interspersed with smoky quartz and biotite. This indicated its presence in an igneous rock. Mineralogists analyzing the rock identified its composition using its properties. Careful examination using optical instruments revealed it's platy form. The albite provided clues to the rock's formation history.
• Metamorphic rocks, such as certain gneisses, often display the presence of albite alongside other minerals like muscovite and garnet. The albite's presence suggests conditions of lower temperature and high-pressure metamorphism. Studying the textures and mineral assemblages helps to understand the rock’s transformation. Such analysis can indicate the process of the rock’s formation. These studies can teach us about Earth's history.
• Thin sections of sandstone revealed rounded grains of quartz and angular fragments of albite, indicating its sedimentary origin. This allowed for determining the sources of sediments. Examination of the grains under a microscope is important. This can provide evidence of its transportation and deposition. This study can further help establish the origin of these rocks.
• In some pegmatites, albite crystals can grow to significant sizes, forming large, well-defined specimens. These large specimens are of great interest to mineral collectors. The crystals often exhibit a pearly luster, and a distinct platy shape. They can be mined. The larger crystals found in pegmatites are evidence of slow cooling environments.
• Albite is often associated with other feldspars, like orthoclase, forming intergrowths or solid solutions within rocks. This interaction leads to distinct textures and mineralogical features. The close association impacts the physical properties. Analysis and determination of the mineral structure is very important. This also helps us understand the chemical evolution of the rocks.