metamorphic
Marble
Recrystallized Carbonate Rock (CaCO3)
Hardness: 3-4 (Mohs scale); Color: White to light grey (in this specimen); Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal (calcite crystals); Cleavage: Perfect rhombohedral (in individual grains); Specific gravity: 2.6-2.8
- Hardness
- 3-4 (Mohs scale)
- Color
- White to light grey (in this specimen)
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 3-4 (Mohs scale); Color: White to light grey (in this specimen); Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal (calcite crystals); Cleavage: Perfect rhombohedral (in individual grains); Specific gravity: 2.6-2.8
Formation & geological history
Formed through the regional or contact metamorphism of sedimentary carbonate rocks, such as limestone or dolostone. This process involves high heat and pressure causing recrystallization of the original minerals into an interlocking mosaic of calcite or dolomite crystals.
Uses & applications
Used widely in construction (countertops, flooring), sculpture due to its relative softness and homogeneity, as a white pigment in paper and toothpaste, and as a soil conditioner in agriculture.
Geological facts
Pure white marble is the result of metamorphism of very pure (silicate-poor) limestone. The characteristic swirls and veins of many colored marble varieties are usually due to various mineral impurities such as clay, silt, sand, or iron oxides.
Field identification & locations
Identify in the field by its sugary (saccharoidal) texture and its reaction to dilute hydrochloric acid (it will effervesce). It is softer than glass and can be scratched by a steel blade. Found in mountainous regions globally, such as Carrara, Italy or the Appalachian Mountains.
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