metamorphic
Black Marble with Quartz Veining
Metamorphosed Limestone (Recrystallized CaCO3)
Hardness: 3-4 (Mohs scale); Color: Black with white or grey veining; Luster: Vitreous to dull (polished in image); Structure: Granoblastic/Massive; Cleavage: Prefers rhombohedral cleavage in calcite crystals; Specific Gravity: 2.6-2.8.
- Hardness
- 3-4 (Mohs scale)
- Color
- Black with white or grey veining
- Luster
- Vitreous to dull (polished in image)
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Physical properties
Hardness: 3-4 (Mohs scale); Color: Black with white or grey veining; Luster: Vitreous to dull (polished in image); Structure: Granoblastic/Massive; Cleavage: Prefers rhombohedral cleavage in calcite crystals; Specific Gravity: 2.6-2.8.
Formation & geological history
Marble forms from the regional or contact metamorphism of limestone or dolostone. High temperatures and pressures cause recrystallization of the original carbonate mineral grains. The black color often comes from organic carbon or bitumen, while the veins are typically quartz or calcite filled fractures during later geological stress.
Uses & applications
Used extensively in decorative construction, floor tiles, countertops, ornamental sculptures, and as tumbled stones for metaphysical cooling or pocket stones.
Geological facts
The white veins are called 'fracture fills' and are evidence of tectonic activity that cracked the stone, allowing mineral-rich fluids to flow through and crystallize. Famous black marbles include Nero Marquina from Spain.
Field identification & locations
Identify in the field by its softness (can be scratched by a steel blade) and its effervescence (bubbles) when touched with dilute hydrochloric acid. It is commonly found in mountain ranges that have undergone significant folding and tectonic activity.
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