sedimentary
Veined Limestone (Micrite) with Quartz/Calcite Veins
Calcium Carbonate (CaCO3) with Silicate or Carbonate inclusions
Hardness: 3-4 (matrix), 7 (veins); Color: Dark grey/blue matrix with white or cream veins; Luster: Dull to earthy; Crystal Structure: Microcrystalline (trigonal); Cleavage: Perfect rhombohedral in calcite veins.
- Hardness
- 3-4 (matrix), 7 (veins)
- Color
- Dark grey/blue matrix with white or cream veins
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (matrix), 7 (veins); Color: Dark grey/blue matrix with white or cream veins; Luster: Dull to earthy; Crystal Structure: Microcrystalline (trigonal); Cleavage: Perfect rhombohedral in calcite veins.
Formation & geological history
Formed in shallow marine environments from the accumulation of lime mud. The white veins are later secondary mineralizations of quartz or calcite that filled fractures caused by tectonic stress.
Uses & applications
Used primarily as crushed stone for construction, decorative gravel, and aggregate. Polished specimens are used in jewelry and as decorative pocket stones.
Geological facts
The 'veins' in the rock are essentially lightning bolts of geological time, showing where the rock cracked and minerals precipitated out of moving groundwater millions of years ago.
Field identification & locations
Look for the distinct contrast between the dark host rock and the white lattice-like veins. Often found on beaches or in riverbeds where water has naturally tumbled the rock smooth.
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