Marble (Calcitic)

Physical Properties

Hardness: 3 on Mohs scale; Color: white to light gray with slight mottling; Luster: vitreous to pearly; Crystal structure: trigonal/rhombohedral; Cleavage: perfect in three directions (not visible in grain); Specific gravity: 2.7

Formation & Geological History

Formed through the regional or contact metamorphism of limestone or dolostone. High heat and pressure cause the recrystallization of carbonate minerals into a dense interlocking mosaic of crystals.

Uses & Applications

Used extensively in construction (tiles, facades), as a flux in metallurgy, for sculpturing, and as a soil treatment in agriculture.

Geological Facts

Marble has been used by sculptors like Michelangelo for centuries because of its relative softness and isotropic properties. It is chemically sensitive to acid rain because of its calcium carbonate content.

Field Identification & Locations

Identify in the field by its sugary (saccharoidal) texture and reaction (fizzing) with dilute hydrochloric acid. It is softer than glass or quartz and can be scratched with a copper penny.

Identified on: 5/2/2026

Mode: Standard