ˈ ̷ ̷ˌ ̷ ̷ noun
1. : a sedimentary deposit that consists largely of dark greenish grains of glauconite often mingled with clay or sand, occurs abundantly in the Cretaceous often little or not at all cemented, and is used as a water softener and as a source of potash
2. : highly siliceous sand that contains a little magnesia and alumina mixed with about one twelfth of its bulk of powdered coal or charcoal and is used when dampened for making foundry molds