metamorphic
Marble
Recrystallized Calcite (CaCO3) or Dolomite (CaMg(CO3)2)
Hardness: 3 on Mohs scale; Color: White to light gray; Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal (granular texture); Cleavage: Perfect rhombohedral (in individual grains); Specific gravity: 2.7
- Hardness
- 3 on Mohs scale
- Color
- White to light gray
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 3 on Mohs scale; Color: White to light gray; Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal (granular texture); Cleavage: Perfect rhombohedral (in individual grains); Specific gravity: 2.7
Formation & geological history
Formed through the regional or contact metamorphism of sedimentary carbonate rocks, such as limestone or dolostone. Increased temperature and pressure cause recrystallization of the original carbonate mineral grains.
Uses & applications
Used extensively in construction for flooring and countertops, in sculpture due to its relative softness and uniformity, and as a source of calcium carbonate for agricultural and industrial chemical processes.
Geological facts
Pure white marble is the result of metamorphism of a very pure (silicate-poor) limestone or dolomite protolith. The characteristic swirls and veins of colored marble are usually due to various mineral impurities like clay, silt, sand, or iron oxides.
Field identification & locations
Identify in the field by its sugary/granular texture and its reaction (fizzing) when exposed to a drop of dilute hydrochloric acid. It is commonly found in mountainous regions where the earth's crust has been folded and subjected to high heat.
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