metamorphic
Quartz-rich limestone or calcitic marble
Calcite (CaCO₃), possibly with quartz (SiO₂)
AI-generated identification · may be incorrectPale cream, massive, dull to weakly sugary luster, with no visible crystals or cleavage in the photograph; calcite has Mohs hardness 3, while quartz-rich areas may reach 7. Calcite should effervesce vigorously in cold dilute hydrochloric acid or vinegar, though a weak reaction may indicate marble or surface alteration.
Identified More metamorphic →
Explore Quartz-rich limestone or calcitic marble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Pale cream, massive, dull to weakly sugary luster, with no visible crystals or cleavage in the photograph; calcite has Mohs hardness 3, while quartz-rich areas may reach 7. Calcite should effervesce vigorously in cold dilute hydrochloric acid or vinegar, though a weak reaction may indicate marble or surface alteration.
Formation & geological history
Likely carbonate sediment originally deposited in a marine environment, then compacted and possibly metamorphosed into marble; age cannot be determined from appearance alone. The rounded shape suggests natural stream/beach wear or handling.
Uses & applications
Limestone is used for cement, aggregate, and agricultural lime; marble is used for building stone and sculpture. This specimen has modest decorative or educational value.
Geological facts
The key distinction is acid reaction: strong fizz indicates calcite-rich limestone, while crystalline texture and weaker reaction suggest marble. Quartz impurities can make the surface harder and more resistant to acid.
Field identification & locations
Commonly found in sedimentary or metamorphic terrains worldwide, including the Appalachians, Alps, and Mediterranean regions. Test an inconspicuous spot with dilute acid and inspect a fresh break for granular calcite crystals.
More like this
