Magnetite Grains in Obsidian

This specimen consists of fine, dark grains of magnetite occurring within or associated with obsidian, a natural volcanic glass formed by the rapid cooling of silica-rich lava. Magnetite commonly crystallises early from cooling magma and may become trapped as microscopic grains or dusty inclusions within obsidian before the melt quenches.

Such specimens are useful for demonstrating igneous processes, particularly the sequence of mineral crystallisation and the contrast between crystalline minerals and amorphous volcanic glass. Although visually modest, magnetite grains in obsidian provide clear evidence of iron-rich mineral phases within silicic volcanic systems.