Limestone Pebble
Sedimentary Rock var. Limestone · Mineral Specimen / Sedimentary Rock
Crystal System
Trigonal (microcrystalline calcite), massive habit
Mineral Group
Carbonates
Chemical Formula
CaCO3
Formation Process
Sedimentary accumulation of skeletal fragments of marine organisms and chemical precipitation in shallow marine waters
About This Crystal
A water-worn, smooth grey pebble with a matte luster and opaque transparency, showing minor pitting and a typical rounded river-stone shape
Physical Characteristics
Grey body color, white streak, no distinct cleavage due to fine-grained massive structure, uneven to conchoidal fracture, specific gravity around 2.7, brittle tenacity
Optical Properties
Biaxial negative for calcite crystals composing the mass, highly birefringent under microscopic examination, singly refractive as a bulk rock aggregate
Hardness & Durability
Origin Region
Found globally in marine sedimentary environments, riverbeds, and beaches
Hardness & Durability
Mohs hardness of 3, low durability against acids, fair wearability but too soft for active jewelry
Care & Maintenance
Clean with mild soapy water, avoid acidic cleaners as calcium carbonate reacts with acids, store separately from harder minerals
Rarity & Value
Extremely common worldwide, minimal monetary value, no treatments applied
Special Characteristics
Effervesces (fizzes) when exposed to dilute hydrochloric acid due to the release of carbon dioxide from calcium carbonate
Lore & History
Historically used as a foundational building material (e.g., pyramids, ancient architecture) and in agriculture; in metaphysical lore, limestone is sometimes associated with grounding, stability, and ancient earth wisdom