1. a dark green to black mineral that is a common type of amphibole, found in igneous and metamorphic rocks
Usage: geology

Examples

• The granite contained large crystals of hornblende that gave it a speckled appearance.
• Hornblende is easily identified by its dark color and prismatic crystal shape.
• The metamorphic rock was composed mainly of quartz, feldspar, and hornblende.
• Geologists use hornblende as an indicator mineral when studying rock formation.
• The hornblende crystals in the sample showed perfect cleavage at 60-degree angles.
• Under the microscope, hornblende appears pleochroic, changing color as the stage rotates.