Marl

“Where clay meets calcium”

Sedimentary

Marl is a sedimentary rock that's a natural mixture of clay and calcium carbonate (lime), typically forming in shallow marine or freshwater environments. For centuries it's been spread on agricultural fields to improve soil quality, a practice dating back to Roman times.

Composition

calcite, clay minerals, quartz, dolomite

Where Found

Champagne region (France), White Cliffs area (England), Niobrara Formation (Kansas, USA), Denmark

Mohs Hardness

2-3

Fun Fact

The famous chalky soils of the Champagne wine region are actually marl, and winemakers credit these soils with giving their sparkling wines their distinctive minerality.