noun
- Plural of alumstone; a mineral or rock containing alum, historically mined and processed for use in dyeing, tanning, and other industrial applications.
Usage: chiefly historical; technical/geological
Examples
- Medieval dyers relied on alumstones imported from the Mediterranean to fix colors in cloth.
- The alumstones quarried in this region were ground and processed to extract alum salts.
- Alumstones were a valuable commodity in the textile industry before synthetic alum became widely available.
- Geologists identified deposits of alumstones in the volcanic formations of the area.