1. a clay mineral that is a common component of sedimentary rocks and soils
Usage: geology; mineralogy

Examples

• The soil sample contained high concentrations of illite.
• Illite is often found in marine sediments.
• The clay’s properties were attributed to its illite content.
• Geologists identified illite as the dominant mineral in the shale.
• Illite forms through the weathering of feldspars and micas.