metamorphic
White Marble (Tumbled)
Recrystallized Calcite (CaCO3)
Hardness: 3 on Mohs scale; Color: Pure white to off-white; Luster: Waxy to vitreous; Crystal Structure: Trigonal (hexagonal scalenohedral); Cleavage: Perfect rhombohedral; Specific Gravity: 2.71
- Hardness
- 3 on Mohs scale
- Color
- Pure white to off-white
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 3 on Mohs scale; Color: Pure white to off-white; Luster: Waxy to vitreous; Crystal Structure: Trigonal (hexagonal scalenohedral); Cleavage: Perfect rhombohedral; Specific Gravity: 2.71
Formation & geological history
Formed from the regional or contact metamorphism of limestone or dolostone. High heat and pressure cause the original carbonate mineral grains to recrystallize into a dense interlocking map of calcite crystals. Geological age varies by deposit, ranging from Precambrian to Cenozoic.
Uses & applications
Used widely in construction for countertops and floor tiles, sculpture, as a soil conditioner (lime), and in the pharmaceutical industry (antacids). Tumbled pieces like this are popular for home decor, vase fillers, and landscaping.
Geological facts
Pure white marble is the result of metamorphism of a very pure (silicate-poor) limestone. The famous Taj Mahal is constructed almost entirely of white Makrana marble. Because it is composed of calcite, it will effervesce (fizz) when in contact with dilute hydrochloric acid.
Field identification & locations
Identify in the field by its softness (can be scratched by a copper penny or steel knife) and its reaction to acid. It is commonly found in mountainous regions such as the Italian Alps (Carrara), Greece, and Vermont, USA. For collectors, look for the sugary texture of the crystal grains.
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