- Hoboken, Hudson County, New Jersey, United States1
- Howes Cave, Cobleskill, Schoharie County, New York, United States1
- Ilfeld, Thuringia, Germany1
- India1
- Iquique, Tarapaca, Chile1
- Kentucky1
- Labrador, Newfoundland and Labrador, Canada1
- Leadhills, South Lanarkshire, Scotland, United Kingdom1
- Lewes, East Sussex, England, United Kingdom1
- Lewes, Sussex, England, United Kingdom1
- Lockport, Niagara County, New York, United States1
- Lubietova, Banskobystricky, Slovakia1
- Magnet Cove, Hot Spring County, Arkansas, United States1
- Marlboro County (S.C.)1
- Matlock, Derbyshire, England, United Kingdom1
- Middletown, Middlesex County, Connecticut, United States1
- Midlands1
- Milos, Nisos, Cyclade Islands, Aegean Islands, Greece1
- Mississippi1
- Mount Vesuvius, Napoli province, Campania, Italy1